Mixings, Lifetimes, Spectroscopy and Production of...

Mixings, Lifetimes, Spectroscopy and Production of b-quarks

Kevin PittsUniversity of Illinois

(mostly hadron collider results)

Lepton-Photon 2003 Fermilab August 12, 2003

Kevin Pitts B BR, lifetimes, mixing slide 2

OutlineIntroduction- B physics at hadron machinesHeavy flavor production

charm cross sectionLifetimesB hadron massesBranching ratios

Bs→K+K-, Λb→Λcπ-, Bs→Dsπ+

MixingBd , Bs

Summary

Notation:

Bd = B0 = |bdÒ

Bu = B+ = |buÒ

Bs = |bsÒ

Bc = |bcÒ

Λb = |udbÒ


B Physics at Hadron Machines

Enormous cross-section~100 µbarn total~3-5 µbarn “reconstructable”At 4x1031cm-2s-1 ⇒ ~150Hz of reconstructable BB!!

All B species producedBu,Bd,Bs,Bc,Λb,…

Production is incoherentMeasure of B and B not required

Large inelastic backgroundTriggering and reconstruction are challenging

Reconstruct a B hadron, ~20-40% chance 2nd B is within detector acceptancepT spectrum relatively soft

Typical pT(B)~10-15 GeV for trigger+reconstructed B’s …softer than B’s at LEP!

Pros ConsFlavor Creation (annihilation)

q b

q b

Flavor Creation (gluon fusion)

bg

g bFlavor Excitationq q

bg

b

Gluon Splitting

bg

g g

b

b’s produced by strong interaction, decay by weak interaction

Production:

Disclaimer: acceptance comments relevant to “central” detectors like DØ and CDF


DetectorsBoth detectors

silicon microvertex detectorsaxial solenoidcentral trackinghigh rate trigger/DAQ systemcalorimeter & muon systems

DØExcellent electron & muon IDExcellent tracking acceptance

CDF Silicon vertex triggerParticle ID (TOF and dE/dx)Excellent mass resolution

CDF silicon detector installation

DØ fiber tracker installation


commissioning

data for physics

Typical detector efficiency ~85-90%

Luminosity used for HF analyses 6−140 pb-1

~220 pb-1 on tape per experiment

first data for analyses

Ap

ril

20

01

Feb

20

02

Jul

20

02

Collider Run IIA Integrated Luminosity


Heavy Flavor Cross SectionsTevatron B Cross sections measured at sqrt(s)=1.8TeV (1992-1996) consistently higher than NLO calculation

Theoretical work is ongoingFragmentation effectsSmall x, threshold effectsProposed beyond SM effects

What can experiments do?Measure more cross sections- sqrt(s)=1.96 TeV- go to lower pT(B)

Look at bb correlationsMeasure the charm cross section

Integrated cross sections

XX


SVT incorporates silicon info in the Level 2 trigger…select events with large impact parameter!

Uses fitted beamlineimpact parameter per trackSystem is deadtimeless:

~25 µsec/event for readout + clustering + track fitting

-500 -250 0 250 500

35µm ⊕ 33µmresol ⊕ beam

⇒ σ = 48µm

SVT impact parameter (µm)

CDF Silicon Vertex Tracker (SVT)

d = impact parameter

Primary Vertex

Secondary Vertex

BLxy

Lxy ≥ 450µmPT(B) ≥ 5 GeV


]2

) [GeV/cπ)-M(KππM(K0.14 0.15 0.16

2E

ntr

ies

per

0.3

MeV

/c

0

200

400

600

800+π-K→0, D+π0D→+D*

6GeV/c≥Tp

85±)= 5515+

N(D*

-1CDF Run II Preliminary 5.8 pb

]2

) [GeV/cπ)-M(KππM(K0.14 0.15 0.16

2E

ntr

ies

per

0.3

MeV

/c

0

200

400

600

800

CDF charm yields Trigger on displaced tracks, accepts both bottom & charm.Reconstruct large samples of charm hadrons >85% prompt charm!

]2

) [GeV/cππMass(K1.7 1.8 1.9 2

2E

ntr

ies

/ 2 M

eV/c

0

1000

2000

+π+π-K→+D

6GeV/c≥Tp

294±)=28361+

N(D


]2

) [GeV/cππMass(K1.7 1.8 1.9 2

2E

ntr

ies

/ 2 M

eV/c

0

1000

2000

]2

) [GeV/cπM(KK1.8 1.9 2 2.1

2E

ntr

ies

per

5 M

eV/c

0

100

200

+K-

K→φ,+πφ→s+,D+D

42±) = 502+

N(D

8GeV/c≥Tp

43±) = 851s+

N(D


]2

) [GeV/cπM(KK1.8 1.9 2 2.1

2E

ntr

ies

per

5 M

eV/c

0

100

200

Yields shown for 5.8pb-1


) [GeV/c]0(DTp5 10 15 20

Dat

a/T

heo

ry

0

0.5

1

1.5

2

2.5

) [GeV/c]0(DTp5 10 15 20

Dat

a/T

heo

ry

0

0.5

1

1.5

2

2.5

CDF Run II preliminary Data/Theory Cross Section0D

CDF Prompt charm Cross Section

Prompt charm cross section result submitted to PRL hep-ex/0307080See poster by Chunhui Chen

Calculations shown are Cacciari & Nason hep-ph/0306212Observations:

Data on the “upper edge” of theory for D0 (shown), D+ and D*. Trend similar to that seen in B cross section measurements.

data/theory for Bdata/theory for D0


CDF Run II Preliminary

0 4 8 12 16pT(J/ψ) GeV/c

10-1

1

101

102

dσ/d

p T(|y

|<0.

6) .

Br(

J/ψ

→µµ

) nb

/(G

eV/c

)

Data with stat. uncertainties

Systematic uncertainties

Inclusive J/ψLarge yield, clean signals

Acceptance down to pT =0 GeV!χc signals also observed

Inclusive lifetime shows B→J/ψX fraction to be 15-20% (>80% direct charm)See Tomasz Skwarnicki’s quarkonia talk

cmτc-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

mµE

vts/

12.5

1

10

102

103

104

Data

Sideband

B Signal

B Signal + background

Inclusive B Lifetime

mµ 14(syst) ± 4(stat) ± = 468 τc

Run II Preliminary∅D

Inclusive lifetime also important for understanding lifetime systematics

( )/pp J Xσ ψ→

CDF Run II Preliminary

2.70 2.90 3.10 3.30 3.50M(µµ) GeV/c2

0

10000

20000

30000

40000

Eve

nts/

5 M

eV/c

2

299,800 ± 800 EventsLuminosity = 39.7 pb-1

Width = 24 MeV/c2

0.7 0.8 0.9 1 1.1 1.2

lifetime ratio

τ(b baryon)/τ(B0)

0.784±0.0340.9 - 1.0

τ(Λb)/τ(B0) 0.798±0.0520.9 - 1.0

τ(Bs)/τ(B0) 0.949±0.0380.99 - 1.01

τ(B−)/τ(B0) 1.073±0.0141.03 - 1.07

All lifetimes equal in spectator model.Differences from interference & other nonspectator effects

Heavy Quark Expansion predicts the lifetimes for different B hadron species

Measurements:B0,B+ lifetimes measured to better than 1%!Bs known to about 4%LEP/CDF (Run I) Λb lifetime lower than HQE prediction

Tevatron can contribute to Bs,Bc and Λb (and other b-baryon) lifetimes.

B Hadron Lifetimes

B hadron Average lifetime (ps) B0 1.534±0.013 B+ 1.653±0.014 Bs 1.439±0.053 Bc 0.18

0.160.46+−

Λb 0.0780.0761.233+

−

0B B B Bs cbτ τ τ τ τ

+ ≥ ≈ > Λ

Heavy Flavor Averaging Grouphttp://www.slac.stanford.edu/xorg/hfag/index.html

LEP


∆t (ps)

entr

ies

/ 0.8

ps

1

10

10 2

10 3 B 0

1

10

10 2

10 3

−20 −15 −10 −5 0 5 10 15 20

B−

Belle B+ & B0 Lifetime29 fb-1 fully reconstructed decays

7863 B0

12047 B+

Lifetime measured in ∆t(see Tom Browder’s talk)

Results:τ(B0)=1.554±0.030(stat.)±0.019(syst.)psτ(B+)=1.695±0.026(stat.)±0.015(syst.)psτ(B+)/τ(B0)=1.091±0.023(stat.)±0.014(syst.)ps

Tails are well-modeled

(GeV)ΛΨJ/M4.5 5 5.5 6 6.5 7

Eve

nts

/ 75

MeV

0

20

40

60DØ Run II Preliminary

14±Sig.=5625 MeV±Mass=5600

20 MeV± = 86σ

D0 RunII Preliminary, Luminosity=114 pb-1

0

100

200

4.8 5 5.2 5.4 5.6 5.8 6M(J/ψ K*0) GeV/c2

Bd → J/ψ K*(892)0

N = 509 ± 37

Yields in B→J/ψX Modes

2candidate mass, GeV/c5.20 5.25 5.30 5.35 5.40

2ca

nd

idat

es p

er 5

MeV

/c

0

50

100

150

200

250

300

350

400 + Kψ J/→ + B

CDF Run II Preliminary -1 138 pb≈L

47 sig.±1513candidates

2candidate mass, GeV/c5.20 5.25 5.30 5.35 5.40

2ca

nd

idat

es p

er 5

MeV

/c

0

50

100

150

200

250

300

350

400

Fit prob: 0.3%

CDF Run II Preliminary, L = 65 pb-1

5.10 5.20 5.30 5.40 5.500

40

80

120

160

B0 Candidate Mass (GeV/c2)

Eve

nts/

10M

eV/c

2

Control Sample for ΛB Lifetime

B0 → J/ψ Ks0

246± 16 signal candidates

Trigger on low pTdimuons (1.5-2GeV/µ)Fully reconstruct

J/ψ, ψ(2s)→µ+µ−

B+→ J/ψK+

B0 → J/ψK*, J/ψKs

Bs → J/ψφΛb→ J/ψΛ

B +→ J/ψK+

B 0→ J/ψK*

Λb→ J/ψΛ

B 0→ J/ψKs

D0 RunII Preliminary, Luminosity=114 pb-1

0

100

200

300

400

4.8 5 5.2 5.4 5.6 5.8 6M(J/ψ K±) GeV/c2

B± → J/ψ K±

N = 1235 ± 52

B +→ J/ψK+


B+, B0 Lifetimes in J/ψ Modes

DØ 1.51 (stat.) ± 0.2 (syst.) psCDF 1.51 ± 0.06(stat.) ± 0.02 (syst.) ps

ct, cm-0.1 0.0 0.1 0.2 0.3

mµca

nd

idat

es p

er 5

0

1

10

102

103

104 *0 Kψ J/→ 0 B

CDF Run II Preliminary -1 138 pb≈L

data

ct (Sig)

) Sct (Bkg

) Lct (Bkg

ct, cm-0.1 0.0 0.1 0.2 0.3

mµca

nd

idat

es p

er 5

0

1

10

102

103

104

Fit prob: 22%

DØ 1.65 ± 0.08(stat.) (syst.) ps CDF 1.63 ± 0.05(stat.) ± 0.04 (syst.) ps

0.190.17

+−

τ(B+)

τ(B0)

cm-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3

mµE

ven

ts/ 4

0

1

10

102

103

data∅DTotal Fit B+ signalBackground


m (stat) +29/-37 (syst)µ 25 ± = 495 +Bλ

Lifetime +B

0.100.12

+−

115pb-1

xy xy B

T

L L mct

pβγ= =

Proper decay length:


, cmτcandidate c-0.05 0 0.05 0.1 0.15 0.2 0.25

Eve

nts

/0.0

05 c

m

1

10

102

DO Run II Preliminary

φ ψ J/→ sB

candidate mass, GeV5.1 5.2 5.3 5.4 5.5 5.6 5.7

Eve

nts

/20

MeV

0

5

10

15

20

25

30

DO Run II Preliminary

φ ψ J/→ sB

Bs LifetimeBs→J/ψφ, with J/ψ→µ+µ− and φ→K+K−

xy xy B

T

L L mct

pβγ= =

Lxy

µ+

K+

µ−

K−primary

0.190.16

+−

(uncorrected for CP composition)

Interesting Bs physics:

Search for CPV in Bs→J/ψφ…sensitive to new physicsWidth difference ∆Γ

Bs mixing (later in talk)

DØ (115pb-1): (shown here)

τ(Bs)=1.19 (stat.) ±0.14(syst.) ps

τ(Bs)/τ(B0) =0.79±0.14

CDF (138pb-1):

τ(Bs)=1.33±0.14(stat.) ±0.02(syst.) ps


Λb LifetimeUse fully reconstructed Λb→J/ψΛwith J/ψ→µ+µ− and Λ→pπ−

Previous LEP/CDF measurements used semileptonic Λb→Λclν- Systematics different

CDF Run II Preliminary 65pb-1

Unbinned Likelihood Fit To ΛB Lifetime

1

101

102

103

J/ψ cτ µm

Eve

nts/

40µm

cτ=374±78(stat)±29(syst)µm

signal region fit

background fit

CDF Run II Preliminary 65pb-1

ΛB mass sideband

-1000 0 1000 2000

1

101

102

103 CDF

DØ

) Proper Decay Length (cm)Λ,ψ(J/-0.1 0 0.1 0.2

Eve

nts

/0.0

1 (c

m)

10-1

1

10

102

DØ Run II Preliminary

0.12 ps±-0.180.21=1.05τ

( ) ( ) ( )0.210.181.05 . 0.12 . psb stat systτ +

−Λ = ±

( ) ( ) ( )1.25 0.26 . 0.10 . psb stat systτ Λ = ± ±

56±14 signal

CDF 46±9 signal

65pb-1

115pb-1

Lxy

µ+p

µ−

π−

primary


B Hadron MassesMeasure masses using fully reconstructed B→J/ψX modesHigh statistics J/ψ→µ+µ− and ψ(2s)→J/ψπ+π− for calibration.Systematic uncertainty from tracking momentum scale

Magnetic fieldMaterial (energy loss)

B+ and B0 consistent with world average.Bs and Λb measurements are world’s best.

]2 candidate mass [GeV/cbΛ5.3 5.4 5.5 5.6 5.7 5.8 5

2E

ven

ts/6

MeV

/c

0

2

4

6

8

10

12

14

16 7±)= 38bΛN(

-1CDF Run II Preliminary 70 pb

Λ ψ J/→BΛ

]2

candidate mass [GeV/csB5.10 5.15 5.20 5.25 5.30 5.35 5.40 5.45 5.50 5.55 5.60

2E

ven

ts/5

MeV

/c

0

5

10

15

20

25

30

8.2±N(Bs)=71.8

-1CDF Run II Preliminary 80 pb

φψ J/→sB

CDF result: M(Bs)=5365.50 ±1.60 MeVWorld average: M(Bs)=5369.60 ±2.40 MeV

CDF result: M(Λb)=5620.4 ±2.0 MeVWorld average: M(Λb)=5624.4 ±9.0 MeV


OutlineIntroduction- B physics at hadron machinesHeavy flavor production

charm cross sectionLifetimesB hadron massesBranching ratios

Bs→K+K-, Λb→Λcπ-, Bs→Dsπ+

MixingBd , Bs

Summary


280±26 eventsµ = 5.252(4) GeV/c2

σ = 41.0(4.0) MeVc2

M(ππ)

charmless two-body decayslonger term Bs modes help extract unitarity angle γ (see Hassan’s talk)

Signal is a combination of:B0→π+π− BR~5x10-6

B0→K+π− BR~2x10-5

Bs→K+K− BR~5x10-5

Bs→π+K− BR~1x10-5

RequirementsDisplaced track triggerGood mass resolutionParticle ID (dE/dx)

CDF B→h+h−

}Υ(4s),Tevatron

}Tevatron

Did you ever think this physics could be done at a hadron collider?

tree

Vub•

γ

α

β

penguin

π+π− hypothesis


BR(Bs→K+K−)Simulation

Bd→KπBs→KKBd→π πBs→K π

320±60 eventsµ = 5.252(2) GeV/c2

σ = 41.1(1.9) MeV/c2

M(ππ)

Sep.~1.3σ

CDF RunII Preliminary

(dE/dx – dE/dx(π))/σ(dE/dx)

D* D0π,D0 Kπ

kinematics & dE/dx to separate contributions

see poster by Diego Tonelli

First observation of Bs→K+K− !!

Result:( )( )

2.71 1.15s

d

BR B K K

BR B K π

±

±

→= ±

→

∓

∓

3±11(stat.) ±17(syst)Bs→Kπ

90±17(stat.) ±17(syst)Bs→KK

39±14(stat.)±17(syst)B0→ππ

148±17(stat.)±17(syst)B0→Kπ

Yield (65 pb-1)modeFitted contributions:

includes error on fs/fd


Reflections, Satellites and All That

]2

Mass [GeV/c+π0

D

4.6 4.8 5.0 5.2 5.4 5.6

2E

ntrie

s pe

r 10

MeV

/c

0

50

100

150

200

250

300

350

400

450

]2

Mass [GeV/c+π0

D

4.6 4.8 5.0 5.2 5.4 5.6

2E

ntrie

s pe

r 10

MeV

/c

0

50

100

150

200

250

300

350

400

450 -1CDF Run II Preliminary, L = 119 pb

+π0

D → +about 1900 B

Vertex trigger sample

reconstruct: B−→D0π−

Clear peak seen, sidebands have interesting structure

-“horns” coming from D*-Reflection from B−→D0K−

(reconstruct K as π)

Work in progress, must understand these contributions to extract BR

]2

Candidate Mass [GeV/c4.6 4.8 5.0 5.2 5.4 5.6

2C

andi

date

s pe

r 10

MeV

/c0

20

40

60

80

100

120

other

+ K0*

D → +B

+π -* D→ 0B

+π 0*

D → +B

+ K0

D → +B

+π 0

D → +B

]2

Candidate Mass [GeV/c4.6 4.8 5.0 5.2 5.4 5.6

2C

andi

date

s pe

r 10

MeV

/c0

20

40

60

80

100

120

CDF Run II Monte Carlo


CDF Λb→Λcπ with Λc→pKπBackgrounds: real B decaysReconstruct π as p: Bd → D−π+→K+π−π−π+

Use MC to parametrize the shape.Data to normalize the amplitudeDominant backgrounds are real

heavy flavorproton particle ID (dE/dx)

improves S/B

)2

) (GeV/cπcΛmass (5 5.5 6 6.5 7

)2E

vent

s / (

0.0

2 G

eV/c

0

10

20

30

40

50

candidatesπ cΛ → bΛ 11 ±83

Four-prong B reflections

Other B meson decays

decaysbΛOther

KcΛ → bΛ

Combinatorial background

Four-prong B reflections

Other B meson decays

decaysbΛOther

KcΛ → bΛ

Combinatorial background

CDF II Preliminary )-1

CDF Run II Preliminary (Luminosity 65 pb

(with dEdx cut on proton)

Fitted signal:

( )6796 13( .) .

bN stat syst+

Λ −= ±

BR(Λb Λc π±) = (6.0 ±1.0(stat) ± 0.8(sys) ± 2.1(BR) ) 10-3

New Result !0

( )( )

b baryon b c

b d

f BRf BR B D

σ πσ π

+ −

− +

× × Λ → Λ

× × →Measure:


Bd MixingBd mixing measured with great precision

World average now dominated by Babar and BelleB0

b d

dW−

t

W+

tb

B0

•

••

•

Vtb~1 Re(Vtd)≈0.0071

Babar ∆md result using hadronic B decays

|∆t| (ps)

Am

ix

c)BABAR

-1

-0.5

0

0.5

1

0 5 10 15 20

Bd fully mixes in about 4.1 lifetimes


Towards Bs Mixing

Measurement of ∆ms helps improve our knowledge of CKM triangle.Combined world limit on Bs mixing

∆ms>14.4ps-1 @95%CLBs fully mixes in <0.15 lifetime!!!

Bs oscillation much faster than Bdbecause of coupling to top quark:

Re(Vts)≈0.040 > Re(Vtd)≈0.007

B0

b s

sW−

t

W+

tb

B0

•

••

•

Vtb~1 Re(Vts)≈0.04

Combined limit comes from 13 measurements from LEP, SLD & CDF Run I

γα

β

∆ms/∆md


Measuring MixingBs or Bs at the time of production?

Initial state flavor taggingTagging “dilution”: D=1-2wTagging power proportional to: εD2

Bs or Bs at the time of decay?Final state flavor taggingCan tell from decay products (e.g. )

YieldsNeed lots of decays (because flavor tagging imperfect)

Proper decay time

Need decay length (Lxy) and time dilation factor (βγ =pT/mB)Crucial for fast oscillations (i.e. Bs)

s sB D π− +→

( ) T

xy

pBct

xy xy B

TL

T T

L L mct m

p ppct

σσ σ

βγ

= ⊕

=

= uncertainty

Typical power (one tag): εD2 = (1%) at TevatronεD2 = (10%) at PEPII/KEKB


Flavor TaggingStrategy: use data for calibration (e.g. B±→J/ψK±, B→lepton)

“know” the answer, can measure right sign and wrong sign tags.

DØ Results:Jet charge εD2=(3.3±1.1)%Muon tagging εD2=(1.6±0.6)%

), GeV+ ) - M(Bπ, +M(B0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Nu

mb

er o

f E

ven

ts/5

0 M

eV b

ins

0

10

20

30

40

50

60

70 D0 RunII Preliminary

+π +B -π +B

17±#events in peak = 65

0.016 GeV.± ) = 0.426 +

) - M(B-π, +

M(B

CDF Results:

Same-side (B+) εD2=(2.1±0.7)%(B+/B0/Bs correlations different)Muon tagging εD2=(0.7±0.1)%

invariant mass [GeV]+π -π +K

4.6 4.8 5 5.2 5.4 5.6

Num

ber

of e

ntrie

s / 1

0 M

eV

0

50

100

150CDF Run II Preliminary +π 0 D→ +B

31 events±Right Sign, 563

26 events±Wrong Sign, 396

“same-side” tagging


Bs Yields: CDF Bs→Dsπ+

New measurement !Previous limit set by OPAL: BR (Bs Ds π± ) < 13%

BR(Bs Ds π±) = ( 4.8 ± 1.2 ± 1.8 ± 0.8 ± 0.6) ×10-3

(Stat) (BR) (sys) (fs/fd)BR result uses less data than shown in plot.

Bs→Dsπ− with Ds →φπ+ and φ→K−K+

]2

Mass [GeV/c+π-sD

5.0 5.5

2E

ntrie

s pe

r 20

MeV

/c

0

10

20

30

40

50

]2

Mass [GeV/c+π-sD

5.0 5.5

2E

ntrie

s pe

r 20

MeV

/c

0

10

20

30

40

50

-1CDF Run II Preliminary, L = 119 pb+π-

s D→ 0sabout 100 B

]2

Candidate Mass [GeV/c5.0 5.5

2C

andi

date

s pe

r 10

MeV

/c

0

10

20

30

40

50

60

70

80

otherν+ l-

s D→ 0sB

+π -*s D→ 0

sB

+ρ -s D→ 0

sB

+ K-s D→ 0

sB

+π -s D→ 0

sB

5.0 5.50

10

20

30

40

50

60

70

80CDF Run II Monte Carlo


)[GeV]π-K+

Mass(K

1.8 1.9 2.0 2.1 2.2

Num

ber

of C

andi

date

s / 0

.01

[GeV

]

0

50

100

150

200

250

-1CDF RunII Preliminary 60 pb

DsXν l→ sB-K

+ K→ φ, πφ → sD

22± : 385 DsN 19± : 112 D+N

Semileptonic Bs YieldsD0 RunII Preliminary, Luminosity = 6.2 pb-1

0

50

100

1.8 2 2.2M(φ π+) GeV/c2

B → µ- φ π+ X

279±32 Ds→φ π+

72±29 D+→φ π+

µ- φ π+

µ- φ π-

Plots show: Bs→Dsl−ν with Ds →φπ+ and φ→K−K+

(will also reconstruct Ds →K*0K+ and Ds →KsK+)


DØ B Semileptonic Lifetime

τ(B) = 1.46 ± 0.08(stat.) ps

[cm]τc-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

Eve

nts

/(0.

0085

cm

)10

-1

1

10

102

103

data∅D

Total Fit

Signal

Background


m (stat) µ 25 ±(B) = 438 τc

X Lifetimeµ0B->DB→µ−νµD0X with D0→K−π+

Time dilation factor (βγ) must be corrected for missing ν

12pb-1 of data taken with single muon trigger.

]2

) [GeV/cπMass(K 1.65 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05 2.1

)2E

ven

ts/(

18 G

eV/c

0

200

400

600

800

1000

Mass0D / ndf 2χ 16.68 / 20

Prob 0.6739

Nevents 102.9± 1276

Mean 0.002202± 1.857

Sigma 0.002627± 0.02937

Norm 6.659± 616.6

Slope 0.064± 1.439


Signal fraction = 0.155

Mass0D


Bs SensitivityFrom data, now have some knowledge of the pieces that go into measuring ∆ms

Yields S = # signal eventsFlavor tagging tagging power = εD2

Signal-to-noise S/B = signal/backgroundProper time resolution σt = proper time resolution

The sensitivity formula:

Significance (in number of standard deviations) is “average signficance”

( )22

2

2

s tmS D SSignificance eS B

σε ∆−

=+


CDF Bs Sensitivity EstimateCurrent performance:

S=1600 events/fb-1 (i.e. σeffective for produce+trigger+recon)S/B = 2/1εD2 = 4%σt = 67fs

2σ sensitivity for ∆ms =15ps-1 with ~0.5fb-1 of data- surpass the current world average

With “modest” improvementsS=2000 fb (improve trigger, reconstruct more modes)S/B = 2/1 (unchanged)εD2 = 5% (kaon tagging)σt = 50fs (event-by-event vertex + L00)

5σ sensitivity for ∆ms =18ps-1 with ~1.7fb-1 of data5σ sensitivity for ∆ms =24ps-1 with ~3.2fb-1 of data

∆ms=24ps-1 “covers” the expected region based upon indirect fits.

This is a difficult measurement.There are ways to further improve this sensitivity…

hadronic mode only


Work In ProgressEstimates based current performance plus modest improvements.Further gain is possible on all of these pieces:

σtEvent-by-event vertexLayer 00

Flavor taggingKaon tagging (same-side and opposite-side)

YieldsOther Bs modes (hadronic and semileptonic)Other Ds modesTriggering- Improved use of available bandwidth- Improve available bandwidth- Improve SVT efficiency

Matters most for going to ∆ms > 20 ps-1

Trigger improvements

matter most for yields

It’s doable! It will take time, luminosity and hard work!


Tevatron Bs SensitivityWe know Bs mixing is a difficult measurement.

Estimate shown is based solely CDF sensitivity for the hadronic modes.

DØ will have sensitivity in hadronic mode(opposite muon)Semileptonic modes important, especially at lower ∆ms

DØ and CDF will both contribute to Bs→lepton+Ds

“This is a marathon, not a sprint.”

SM expectation: ∆Γs ∝ ∆msExperiments will also attempt to measure ∆Γs- in untagged samples - by extracting CP even/odd components in Bs→J/ψφ


ConclusionNew cross sections, lifetime and branching ratio measurements from the Tevatron

Beginning to exploit high yields and upgraded detectors- DØ has a new spectrometer- CDF has a new impact parameter trigger

Babar and Belle continue to provide an amazing breadth of B+ and B0 resultsTevatron will contribute knowledge of heavier B hadrons

Many technical challenges have been overcomeLots of work to do

Stay tuned!

Thanks to: B.Abbott, B.Brau, T. Browder, B.Casey, S.Donati, S.Giagu, V.Jain, D.Kirkby, B.Klima, J.Kroll, N.Lockyer, C. Paus, M.Rescigno, M.Shapiro, M.Tanaka and the experimental collaborations.

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