Heavy Flavor Physics at Tevatron Run II

1
Heavy Flavor Physics at Tevatron Run II
Kin Yip

• Introduction (Collider and Detector Upgrade)
• Detector Performance
• First results (lifetimes, masses, )
• Summary
• First International Workshop on Frontier Science
  Charm, Beauty and CP
• Frascati, Oct. 10th, 2002

2
Fermilab
DØ
Chicago ?
CDF
Booster
p
Tevatron
?p
Main Injector Recycler
Run IIa
3
Integrated Luminosities

• Tevatron Center of Mass Energy 1.96 TeV
• Expect 2 fb?1 by end of 2004 (Run IIa),
  15 fb?1 by
  2008 (Run IIb)

CDF
4
Hadron colliders challenge

• Large production cross section
• Even larger inelastic cross section
• (S/B?10-3) ? specialized triggers
• Single lepton triggers
• Dilepton triggers such as
• J/ ? ? ? ? -
• Track triggers moved to L1 (RunII)
• In Run II, L2 trigger on displaced tracks
  using SVX will allow CDF to trigger purely
  hadronic B decays and study such as
• B0 ????, Bs ?Ds?? ...
• Precise 2nd vertex reconstruction

at 2 TeV
at Z0
at ?(4S)

5
CDF Detector Run II Upgrades
All critical components are working well
132 ns front end COT tracks _at_L1 SVX tracks
_at_L2 40000/300/70 Hz no dead time
7-8 silicon layers rf, rz, stereo views z0max45,
?max2 2ltRlt30cm
2 bs or not 2 bs? Double tags essential for
Mtop, H?bb
TOF (100ps_at_150cm)
30240 chnl, 96 layer drift chamber s(1/pT)
0.1/GeV s(hit) 150mm
? coverage extended to ?1.5
Tile/fiber endcap calorimeter (faster, larger
Fsamp, no gap)
6
The Upgraded D? Detector

• Added PreShower detectors, Central (CPS) and
  Forward (FPS)
• Significantly improved Muon System
• New forward proton spectrometer (FPD)
• Entirely new Trigger System and DAQ to handle
  higher event rate

• New tracking devices, Silicon (SMT) and Fiber
  Tracker (CFT), placed in 2 T magnetic field
• Upgraded Calorimeter electronics readout and
  trigger

7
CDF and DØ in Run II

• Stable physics running established in early 2002
• CDF
• Silicon coverage, trigger came together quickly
• CDF L1/L2/L3 trigger 6400/145/25Hz _at_2?1031, ?1
  deadtime
• (BW 40K/300/70)
• 140 trigger algorithms increased rapidly in
  sophistication now quite stable
• DØ
• New detectors such as Silicon and Fiber Trackers
  have worked well
• ? 95 of the SMT and ? 98 CFT channels are
  available for readout
• Triggers have come together gradually L1/L2/L3
  trigger 400/150/50Hz _at_2?1031
• Results shown here are from data recorded
  January-early summer 2002
• Mostly using data of 10.0 pb?1 ( passing some
  stringent good run criteria ) for both
  experiments
• Especially for CDF, already in the mode of very
  stable operation and collecting
  publication-quality data

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Tracking (SMT/CFT) Performance
y
Impact Parameter (DCA) Resolution

• Almost on target with
• no CFT alignment
• 1st pass SMT alignment

DCA
Secondary Vertices
DØ Run 2 Preliminary
KS ? ??-
width 36 ?m ?(beam) 30 ?m ? ? 20 ?m
mass ??-
Improvement expected from alignment with data in
near future
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Muon System Performance
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Hadronic B trigger (revolutionary!)
150 VME boards find fit silicon tracks, with
offline accuracy, in a 15 ms pipeline
Online track impact param.
s48 mm includes 33 mm beamspot
The wisest are the most annoyed by the loss of
time. -Dante

• CDF Secondary Vertex L2 Trigger
• Impact Parameter resolution as planned
• 48 mm (33 mm beam spot transverse size)
• Rf only ? need beamline silicon
• D? is implementing the displaced track L2 trigger
  and should be online in the New Year

gt90
Efficiency
soon
80
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B Physics Cross-sections

• New tracking in 2 Tesla field
• Muon triggers up to ?lt 2

• J/? Cross Section Measurement
• Luminosity 5 pb-1
• First measurement in this rapidity region and ECM

??jet

• b-quark Production Cross Section
• New ECM
• Luminosity 5 pb-1
• Jet ? lt 0.6
• muon tag only, b-content from pTrel fits

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B hadron lifetimes

• Inclusive B lifetime with J/ys
• Fit pseudo-ct LxyyFMCMy/pTy ct45810stat.
  11syst. mm
• (PDG 4694 mm)
• Exclusive B?J/yK lifetime
• ct446 43stat. 13syst. mm
• (PDG 5025 mm)

J/y from B 17
B? 154
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B Lifetime Measurement

• B lifetime measurement from inclusive J/?
• 416 30 signal events
• 2184 47 prompt J/?s
• ?(B) 492 37 ?m (stat. error)
• (PDG ?(B) 469 ?m)

• Exclusive B reconstruction
• B?J/? K
• First time in DØ
• Expect more soon!

5 pb-1
pT(B)gt10 GeV/c
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SVT selects huge charm signals!

• L2 trigger on 2 tracks
• pt gt 2 GeV
• D gt 100 mm (2 body)
• D gt 120 mm (multibody)
• Whopping charm samples!
• Will have O( 107 ) fully reconstructed decays
  in 2/fb data set
• FOCUS todays standard for huge 139K D0?K-p,
  110K D?K-pp
• A substantial fraction comes from b decays

56320 D0
25570 D
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Meson mass measurements

• B masses
• y(2S)?J/y pp- (control)
• Bu? J/y K
• Bd? J/y K0 (K0?Kp-)
• Bs? J/y f (f?KK-)

18.4/pb
Bs?J/yf
More mass plots
CDF 2002 DPDG/s y(2S) 3686.43 0.54
0.9 Bu 5280.6 1.7 1.1 0.8 Bd 5279.8 1.9
1.4 0.2 Bs 5360.3 3.8 -2.1
B??J/yK?
18.4/pb
Bu
2.1 2.9
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Measure Ds, D mass difference
11.6 pb-1

• Ds - D mass difference
• Both D ? fp (f?KK)
• Dm99.280.430.27 MeV
• PDG 99.20.5 MeV
• (CLEO2, E691)
• Systematics dominated by background modeling

2400 events
1400 events
Brand new CDF capability
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Measure Cabibbo-suppressed decay rates

• G(D?KK)/G(D?Kp) (11.170.480.98) (PDG
  10.830.27)
• Main systematic (8) background subtraction
  (E687, E791, CLEO2)
• G(D?pp)/G(D?Kp) (3.370.200.16) (PDG
  3.760.17)
• several 2 systematics
• This measurement has pushed the state of the art
  on modeling SVT sculpting--essential simulation
  tools for both B physics program and e.g. high-pT
  b-jet triggers

Future? - CP violation - mixing - rare decays
Monster Kp reflection here ...
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Toward Bs mixing!
??KK-
B 5612
B ? D0 p

• We observe hadronic B decays!
• Next steps
• Reconstruct Bs? Dsp, Ds ?fp
• Flavor tagging algorithms
• Exploit ? ?2 SVX acceptance, SVT efficiency
  improvements

• Next step
• reconstruct Ds???candidates in lepton events
• Find B0s candidates and measure the proper decay
  time
• Limited proper time resolution due to neutrino

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Flavor Oscillations ( BS ) in Run II

• Expected signal 20,000 Bs?Ds?p , Ds?ppp? with
  Ds? ?f p?, KK ?
• Flavor tag effitiveness ?D2 11 (with Time of
  Flight)
• Proper time resolution st 0.045 ps ? t
  sPT/PT ( SVXII with L00 )
• Average Significance (how many ss)
• Sensitive to xslt63 if S/B2/1
• Sensitive to xslt56 if S/B1/2
• ( using Layer 00 TOF in CDF )
• SM Global fit
• 20 lt xslt 30.8 _at_96 C.L.

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2-body hadronic B decays observed!!
sum Bd?Kp Bs?KK Bd?pp Bs?Kp
CDF II simulation
Width 45MeV
B 339
B ? h h-

• Yield lower than expected (now improved) S/N
  better than expected
• With 2 fb?1 sample, measuring g to 10º may be
  feasible, using Fleischers method of relating
  Bs?KK and Bd?pp, and using b as input

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?0b Lifetime

• Theoretical expectation is
• Measurement is
• Previous measurements used semileptonic modes to
  achieve statistical precision
• Disadvantage is that neutrino is lost, carrying
  with it momentum information
• Fully hadronic mode ?0b?J/? ?0
• BR(?0b?J/? ?0)5x10-4
• Trigger on J/?? ? ? - events, reconstruct ?0?p?
• Expect 15 000 events
• No need to rely on Monte Carlo for momentum
  correction

From B Lifetime Working Group
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?0b Lifetime

• ?0? p?
• Highest pT track assigned the proton mass
• Veto events where M(? ?) consistent with Ks0 mass
• Next step search for ?0? p? candidates in J/????
  events

?0?p?
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Measurement of sin(2?) in Run I

• The minimization of the likelihood function
  yields
• sin2?0.79?0.39(stat)?0.16(syst) Statistical
  error gtsystematics.
• Time integrated measurement
• sin2?0.71?0.63 (stat ? sys)
• Using Feldman and Cousing frequentist approach
• 0ltsin2?lt1 _at_93C.L.

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Sin(2b) Expectations for 2 fb?1
(from the report B Physics at the Tevatron Run
II and Beyond) For a time dependent analysis

• D?
• (S/B 0.75)
• e D2 9.8
• Time resolution
• st 100 fs

• assuming luminosity 2 fb?1
• D? and CDF have similar precisions

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Summary

• Excellent heavy flavor physics prospects for Run
  II at Tevatron
• Both experiments have come together finally
• Heavy flavor physics is probably the least
  affected by the luminosity at Tevatron and the
  broad range of B physics programs include
• Charm Physics (largest sample !)
• flavor oscillations (?mS)
• CP violation sin(2b) in B ? J/? KS
• ?0b lifetime, sin(2a), observing decay modes
  related to ?,
• measuring CP violation in
  oscillation,

perhaps currently unique to Hadron Machine
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How many Bd may we get ?
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Muon Triggers
PT(B)gt 4 GeV and ? lt 3
DØ GEANT/Trig. Sim.
max level 2 rate for all DØ triggers is 1000 Hz
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Sin(2b) via B ? J/? KS

• full reconstruction of final state
• two Vs
• soft pions
• measure decay length
• tag flavor at production

• same side flavor tag
• pion charge

• opposite side flavor tags
• lepton charge
• jet charge

Efficiency (e) and dilution factor (D) D 2 P
- 1 P is the correct tag probability eD2 is the
tags effectiveness
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Flavor Tagging