Post on 30-Dec-2015
description
Some New Results in Heavy Flavor Physics
GBorissov Lancaster University UK
representing DOslash Collaboration
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 2
Many new results in heavy flavors physics
bull Properties of top quark
bull Bs lifetime from BsJψ φ
bull Br(Bs μ+μ-)
bull Bd oscillations
bull Signals in Bs μ νDs
bull Λb lifetime
bull B massesbull Properties of X(3872)
bull Bc lifetime
in this talk
Thanks to excellent performance of Tevatron
accelerator and DOslash detector
talk of ANomerotski
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 3
Tevatron Performance
bull Peak luminosity above 11032 cm-2sec-1 achieved
bull Reliable operation of accelerator in stores ~120 hoursweek
bull Expected peak luminosity 31032 cm-
2sec-1 by 2007bull delivered luminosity to
each experiment ~4-8 fb-1 by the end of 2009
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 5
Integrated Luminosity bull Almost 05 fb-1 recorded in DOslashbull Most of analyses use only 30-50 of this statistics more events available big room for improvement
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 2
Many new results in heavy flavors physics
bull Properties of top quark
bull Bs lifetime from BsJψ φ
bull Br(Bs μ+μ-)
bull Bd oscillations
bull Signals in Bs μ νDs
bull Λb lifetime
bull B massesbull Properties of X(3872)
bull Bc lifetime
in this talk
Thanks to excellent performance of Tevatron
accelerator and DOslash detector
talk of ANomerotski
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 3
Tevatron Performance
bull Peak luminosity above 11032 cm-2sec-1 achieved
bull Reliable operation of accelerator in stores ~120 hoursweek
bull Expected peak luminosity 31032 cm-
2sec-1 by 2007bull delivered luminosity to
each experiment ~4-8 fb-1 by the end of 2009
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 5
Integrated Luminosity bull Almost 05 fb-1 recorded in DOslashbull Most of analyses use only 30-50 of this statistics more events available big room for improvement
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 3
Tevatron Performance
bull Peak luminosity above 11032 cm-2sec-1 achieved
bull Reliable operation of accelerator in stores ~120 hoursweek
bull Expected peak luminosity 31032 cm-
2sec-1 by 2007bull delivered luminosity to
each experiment ~4-8 fb-1 by the end of 2009
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 5
Integrated Luminosity bull Almost 05 fb-1 recorded in DOslashbull Most of analyses use only 30-50 of this statistics more events available big room for improvement
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 5
Integrated Luminosity bull Almost 05 fb-1 recorded in DOslashbull Most of analyses use only 30-50 of this statistics more events available big room for improvement
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 5
Integrated Luminosity bull Almost 05 fb-1 recorded in DOslashbull Most of analyses use only 30-50 of this statistics more events available big room for improvement
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 6
Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 7
Top Quark Mass Measurement
bull New statistics from Run II (~160 pb-1) bull 191 events with lepton + 4 jets selectedbull 4 topological variables used to separate ttbar and
W+jets background They are combined into a single discriminant
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 8
Measurement Methodsbull 4 Jets and W can be combined into 2 top
quarks in 12 possible waysbull Two alternative measurement methods
usedbull Template method
ndash apply cut on discriminant
ndash select best mass hypothesis among all jet permutations
bull Ideogram methodndash discriminant is used to compute the purity of ttbar
candidate on event by event basis
ndash use all jet permutations with weight depending on the χ2 of each combination hypothesis
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 9
Top Quark Mass Resultsbull Consistent preliminary results are obtained
(160 pb-1)
bull Leading systematic uncertainty is from ttbar modeling can be improved in the futre
bull In addition new result published (Nature (429) 638 (2004)) using Run I data (single most precise mass measurement)
)methodIdeogram(GeV)syst(17)stat(855177m
)methodTemplate(GeV)syst()stat(560170m
t
51016t
)pb125RunI(GeV)syst(93)stat(631180m 1t
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 10
Br(tWb)Br(t Wq)
bull This ratio should be close to 1 in the SM assuming unitarity of CKM matrix
bull Should be verified experimentallybull Measurement is performed using a
double tagging technique with b-tagging applied to the t-tbar sample (lepton plus jets)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 11
R=Br(tWb)Br(t Wq) Result
bull Two b-tagging methods are usedndash Counting signed impact parameter
ndash Secondary vertex Tagger
bull Consistent preliminary results are obtained
bull This result is consistent with R=1
)syst()stat(700RVertexSecondary
)syst()stat(650RcountingparameterpactIm110100
270240
170120
340300
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 12
Bs Studiesbull Properties of Bs are not well known yet
bull This particle is not accessible at Υ(4s)bull Have many interesting features
ndash Bs oscillation
ndash Lifetime difference of CP-even and CP-odd state
ndash CP violation ndash very small in SM thus can be sensitive to the new physics
ndash Rare decays may be enhanced
bull Bs is abundantly produced at Tevatron and can be reconstructed in both semileptonic and exclusive decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 13
Bs lifetime measurement
bull In this measurement the decay Bs Jψ φ is used
bull In parallel the lifetime of Bd in Bd Jψ K is measured ndash very similar topology
bull Simultaneous measurement of Bd and Bs lifetimes reduces systematics in τ(Bs) τ(Bd) ratio
bull Important step towards measurement of lifetime difference of CP-even and CP-odd Bs states
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 14
Signal selection
cτσ(cτ) gt 5cτσ(cτ) gt 5
~220 pb-1 of DOslash Run II data used
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 15
Lifetime fitTwo dimensional unbinned likelihood fit is
used
Systematic uncertainties
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 16
Bs Lifetime Results )syst(0030)stat(9800Bτ
Bτ
ps)syst(0230)stat(4731Bτ
ps)syst(0200)stat(4441Bτ
07500700
d
s
05200500d
09800900s
This result agrees with other measurements of τ(Bs)Experiment τ(Bs)
DOslash this measurement
1444+0098-0090plusmn0020
CDF (Run II) prelim 1369 plusmn0100+0008-0010
CDF(Run I) semileptonic 136 plusmn0090+006
-005
ALEPH 147 plusmn014 plusmn008
DELPHI 142+014-013 plusmn003
OPAL 150+016-015 plusmn004
(FNAL-PUB-04225-E submitted to PRL)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 17
Search for Bsμ+μ-
Br(Bdl+l-) Br(Bsl+l-)
l = e(34plusmn23)
middot10-15
(80plusmn35) middot10-14
l=μ(15plusmn09)
middot10-10
(34plusmn05) middot10-9
l=τ(31plusmn19)
middot10-8
(74plusmn19) middot10-7
Standard Model prediction
Br(Bdl+l-) Br(Bsl+l-)
l = e lt 59 middot10-6 lt 54 middot10-5
l=μ lt 15 middot10-7 lt58 middot10-7
l=τ lt 25 lt 50
Current 90CL limits
Rare B decays to leptons have very small expected branching rates in SM
They can be significantly higher in different SM extensions
Example SO(10) symmetry breaking model
Contours of constant Br(Bsμ+μ-)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 18
Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 19
Event Preselection
About 38000 candidates remain after preselection
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 20
Discriminating Variables
bullPointing angle angle between Bs momentum and direction from primary to secondary vertex
bullTransverse decay length significance LTσ(LT)
bullIsolation
22
1RΔtracksalls
s ηΔφΔRΔp)B(p
)B(p
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 21
Optimization Procedure
bull ~80 pb-1 of data is used to optimize the selection
bull Signal band is defined as m(BsDOslash) plusmn 180 MeV (90
MeV is Bsμ+μ- resolution in MC)
bull Signal distributions are taken from MC and background from side bands
bull Perform random grid search of 3 discriminating variables and maximize the sensitivity to the signal
bull Signal region in data is kept as a black box open it only after finalizing and fixing the selection procedure
bull Number of events in side bands is used to estimate the background for Bsμ+μ-
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 22
Surviving Eventscut
Signal MC
exp background
Signal
Pointing angle 8016 573plusmn14 580
Decay length significance
3847 43plusmn12 5
Isolation 3746 37plusmn11 4
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 23
Normalization Channelbull B+Jψ K+ (Jψ μ+μ-) is used for normalizationbull muon selection efficiency cancels in the ratiobull Systematics from discriminating variables significantly
reduced
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 24
Systematic uncertainties
Br(Bsμ+μ-) ResultThis measurement
Existing limit (CDF)
90 CL lt 38middot10-7 lt 58middot10-7
95 CL lt 46middot10-7 lt 75middot10-7
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 25
Preparing for Bs oscillations
bull Bs oscillation measurement ndash very interesting and very difficult task
bull Requires both selection of Bs signal and tagging its initial state (b or bbar)
bull Currently DOslash selects Bs in semileptonic decays
bull We also develop methods of Bs selection in hadronic decays
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 26
Initial State Taggingbull Three different methods are developed
ndash Opposite muon tagging
ndash Opposite jet charge tagging
ndash Same side tagging
bull Their performance is verified in data using Bd oscillation
Same side tagging result
Tagging ε D εD2
opposite muon 005 046 0010
Same side 075 012 0010
Same side + Jet charge
068 015 0015
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)
4 October 2004 GBorissov Dzero Hot Topics FPCP-2004 27
Conclusions
bull Many new results in heavy flavor physics are obtained by DOslash collaboration
bull All of them are competitive or the worldrsquos best measurements
bull DOslash will continue research in this direction with the main emphasis on studies complementary to B-factories ndash those involving B hadron states not produced at the Υ(4s)