Some New Results in Heavy Flavor Physics

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


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



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


Top quark StudiesProvide important constraints on the SM Higgs mass and new physics contribution


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


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


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


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)


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


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


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


Signal selection

cτσ(cτ) gt 5cτσ(cτ) gt 5

~220 pb-1 of DOslash Run II data used


Lifetime fitTwo dimensional unbinned likelihood fit is

used

Systematic uncertainties


Bs Lifetime Results )syst(0030)stat(9800Bτ

Bτ

ps)syst(0230)stat(4731Bτ


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)


Search for Bsμ+μ-

Br(Bdl+l-) Br(Bsl+l-)

l = e(34plusmn23)

middot10-15

(80plusmn35) middot10-14

l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8


Standard Model prediction


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-)


Data samplebull DOslash has very efficient di-muon triggersbull Use data collected in 2002 - April 2004bull Sample corresponds to ~250 pb-1 integrated luminosity


Event Preselection

About 38000 candidates remain after preselection


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


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-


Surviving Eventscut

Signal MC

exp background

Signal

Pointing angle 8016 573plusmn14 580

Decay length significance

3847 43plusmn12 5

Isolation 3746 37plusmn11 4


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



Br(Bsμ+μ-) ResultThis measurement

Existing limit (CDF)

90 CL lt 38middot10-7 lt 58middot10-7



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


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


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)




PowerPoint Presentation

Integrated Luminosity

Top quark Studies


Measurement Methods

Top Quark Mass Results

Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events

Normalization Channel



Initial State Tagging

Conclusions



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




























(160 pb-1)





t

51016t



Br(tWb)Br(t Wq)












270240

170120

340300
















Signal selection





used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions




























(160 pb-1)





t

51016t



Br(tWb)Br(t Wq)












270240

170120

340300
















Signal selection





used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions


Br(tWb)Br(t Wq)












270240

170120

340300
















Signal selection





used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions









270240

170120

340300
















Signal selection





used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions
















Signal selection





used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions



used




Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions



Bτ



07500700

d

s

05200500d

09800900s



1444+0098-0090plusmn0020



-005



OPAL 150+016-015 plusmn004



Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions


Search for Bsμ+μ-


l = e(34plusmn23)

middot10-15


l=μ(15plusmn09)

middot10-10


l=τ(31plusmn19)

middot10-8






l=τ lt 25 lt 50

Current 90CL limits








Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions




Event Preselection






bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions





bullIsolation

22

1RΔtracksalls

s ηΔφΔRΔp)B(p

)B(p











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions











Surviving Eventscut

Signal MC

exp background

Signal



3847 43plusmn12 5




reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions



reduced




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions




















Tagging ε D εD2


Same side 075 012 0010


068 015 0015


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions


Conclusions









Top quark Studies


Measurement Methods


Br(tWb)Br(t Wq)


Bs Studies


Signal selection

Lifetime fit

Bs Lifetime Results

Search for Bsμ+μ-

Data sample

Event Preselection



Surviving Events





Conclusions

Some New Results in Heavy Flavor Physics

Documents

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