Flavor Physics at the Tevatron

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Flavor Physics at the Tevatron
Franco Bedeschi INFN - Sezione di Pisa
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Flavor Physics at the Tevatron
OUTLINE

• Main features of Heavy Flavor production at the
  Tevatron
• Experimental issues
• Basic signals and first round of results
• Masses, lifetimes, branching fractions and
  integrated CP asymmetries
• Other results and future prospects
• Baryons
• Bc search
• Rare decays, mixing
• xs, DG, b, g

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HF at the Tevatron

• Very large production of b/c quarks at the
  Tevaton (ECM 1.96 TeV)!
• b/c-quarks masses much heavier than u, d, s, but
  small relative to ltsgt
• Mc 1.5 GeV/c2
• sc 500 mb
• S/N 10-3
• Mb 5 GeV/c2
• sb 100 mb
• sb 1 nb at B-factories, 7 nb at LEP
• S/N 10-3
• 0.2 at B-factories, 0.14 at LEP

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HF at the Tevatron

• Production more complex than in ee-
• s, t, u-channel and NLOLO
• Motion of CM of primary interaction
• Larger spread over available phase space
• Acceptance
• Looser f and q correlation
• No beam ECM constraint
• HF hadron from hadronization of primary quarks
• All types of b-hadrons produced
• Looser momentum correlations
• Beam renmant
• More background from particles other than HF
  decays

NLO
LO
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Tevatron vs B factories

• In the end comparable amount of usable Bu, Bd
• Pt, h acceptance reduces TeV sample available
• B factories luminosity higher
• NOW ? Tev 250 pb-1, Belle/BaBar 150 fb-1
• Tevatron environment more difficult
• Incoherent b-pair production
• Bs, Bc and HF baryons hard or impossible at B
  factories
• Some measurements are possible only at the
  Tevatron
• Eg. Bs mixing, Bc properties, .
• Other measurements are complementary
• Eg. CP violation angle g

Run 1
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Some History

• First fully reconstructed B mesons observed at a
  hadron collider
• CDF 1992 (2.6 pb-1)
• PRL 68, 3403 (1992)

B ?J/y K
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Run 1

• Successful B physics program at Tevatron during
  run 1

First evidence of sin(2b)
Lifetimes
Mixing
Integrated luminosity 120 pb-1
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Run II Tevatron

• Peak luminosity
• 7x1031
• Delivered/on tape
• 500/400 pb-1
• Analyses based on
• 240 pb-1 gt 2 x Run 1

8.6 fb-1
4.4 fb-1
Base plan no recycler
Tevatron long range plan will deliver 4 8 fb-1
by end of FY 2009
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The Upgraded CDF Detector
Central muon
Central calorimeters
Solenoid
New
Old
Partially new
Front end Trigger DAQ Offline
TOF
Endplug calorimeter
Silicon and drift chamber trackers
Forward muon
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D0 side view
Tracker Silicon, Fiber, 2T Solenoid
Preshower

Calorimeters

New
Forward Muon System
Old
Partially New
p
p-bar
Central Muon System
20 m
Electronics
Front End Electronics Triggers / DAQ
(pipeline) Online Offline Software
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Trigger is the key to B physics

• S/N 10-3 ? need strong signatures
• Leptons from SL decay
• 10 for each mode
• Large mass ? large ptrel
• Leptons from J/Y decay
• B ? J/Y X 1
• J/Y ? m m-, e e- 6 each
• Secondary vertex!
• ctD ctB 300 - 500 mm
• Only way for had. decays

l -
n
W-
b
B
c
D
q
D
q
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CDF SVT trigger

• Need dedicated impact parameter trigger
• CDF SVT trigger operating since 2001
• D0 trigger still being commissioned

Resolution
Efficiency
Online track impact param.
8 VME crates Find tracks in Si in 20 ms with
offline accuracy
s48 mm
80
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PID at CDF

• Time of Flight
• dE/dx in COT and SVX

TOF gt1? K/p separation up to p2 GeV
dE/dx in COT K/p sep. gt1.4?_at_Ptgt2GeV (was 1.2)
1.5 GeV/c
dEdx in Silicon Vertex for low-pt tracks PLAN
combine them all !
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Run II Results

• Large sample of J/y for both CDF and D0 (2.5 M
  events at CDF) -- 20 from B decays
• Calibrate mass scale
• Clean samples of exclusive decays B? J/y X

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X (3872)

• Search for X?ypp-
• Confirm signal from Belle

FERMILAB-PUB-03/393-E
X yield 730 90 cand. (11.6 s)
Y(2S)
m(pp) gt 500 MeV
M 3871.30.7 0.4 MeV
hep-ex/0312021
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Rare decays Bd(s) ? mm-
Best world result for Bs (improves CDF Run I x3)
1 event in the overlap region
Slightly better results than Belle and BaBar for
Bd

• Muon Ptgt1.5-3.0 GeV, etalt0.6
• Blind analysis cuts optimized
• before looking at the signal region

2.0 ? 10-7
1.6 ? 10-7
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Bs ? mm- implications for SUSY
R. Arnowitt et al., PLB 538 (2002) 121, new plot
by B.Dutta
R-parity violating
New limit excludes significant amounts of the
previously allowed SUSY models parameters -
Expect 10-7 with 1fb-1
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Run II Results

• Precision mass measurements
• M(Bu) 5279.100.410.34 MeV/c2
• M(Bd) 5279.570.530.30 MeV/c2
• M(Bs) 5366.010.730.30 MeV/c2
• M(Lb) 5619.7 1.2 1.2 MeV/c2
• Current world best values

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Run II Results

• CDF Lifetimes measurements
• D0 has best measurement of ratio of Bu and Bd
  lifetimes
• t(Bu)/t(Bd) 1.0930.0210.022
• (CDF
• ?Bu/?Bd 1.080 ? 0.042
• ?Bs/?Bd 0.890 ? 0.072)
• Consistent and only slightly worse than BaBar PDG
  result
• New technique used fitting the ratio of lifetime
  distributions in semileptonic decays

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Run II Results

• D0 lifetime ratio determination
• m-DX mostly Bd
• m-D0X mostly Bu
• Fit ratio rN(mD)/N(mD0) in 8 visible lifetime
  bins
• Account for feed-down from D using MC
• Shows power of large statistics semileptonic
  samples

Example of lifetime bin
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Toward DGs

• Lifetime difference of two CP eigenstates of Bs
  can be large in SM 10
• Related to Dms DGs 3.7x10-3 Dms
• Easier to measure as Dms gets harder!
• Dms 24 ps-1 ? DGs /Gs 15
• Best measurement from comparing a CP specific
  decay with a flavor specific decay (roughly
  50-50)
• e.g. CP specific Bs?J/y f mostly CP even
• Need to measure fraction of CP even with angular
  analysis
• e.g. Flavor specific Bs?Dsp, Bs?lnDs

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Run II Results

• Polarization analysis consistent with B factories
  for Bd?J/y K0
• Best measurement for Bs ? J/y f
• Important step toward DGs
• A0, A// are CP-even 75

Bd?J/?K
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The Bc, rediscovered
CDF Run1
Box still closed for blind analysis of J/y p (10
of J/y ln)
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Run II Results

• Large samples of hadronic exclusive decays of all
  beauty and charm hadrons at CDF
• Measure relevant BR
• Start understand how to measure lifetimes
• Prime samples for mixing measurements, in
  particular Bs
• Significant samples of 2 body decays
• Measure BRs and integrated CP asymmetries
• Basic samples for future g measurements

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Run II Results D0 BR and ACP

• Clean sample of 200 k D0 from D?D0 psdecay
• Charge of soft pion tags initial D0 type

Best measurements! Better than FOCUS 03
BR(D0?KK)/BR(D0?Kp) 9.96 0.11(stat) 0.12(syst)
BR(D0?pp)/BR(D0?Kp) 3.6080.054(stat)
0.040(syst) ACP(D0?KK) 2.0 (1.7) 1.2 (stat)
0.6 (syst) ( norm. to D?Kp) ACP(D0?pp) 1.0
(0.5) 1.3 (stat) 0.6 (syst)
pp
KK
Kp
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Run II Results

• Now going for BR and ACP of D? ppp - No
  experiment ever had gt1500 ev
• Expect 6k events after flavor tag
• BR known at 10 will become 1
• Unique possibility to see ACP in Charm

190 pb-1
55,000 events !
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Run II Results
Bd?D-?

• - MC templates used to fit mass spectrum.
• - B ?DK is another mode of interest for CP
  analysis.

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?b??c? with ?c?pK?

• Backgrounds real B decays
• Reconstruct p as p Bd ? D?p?Kp?p?p
• Use MC to parametrize the shape.
• Data to normalize the amplitude
• Dominant backgrounds are real HF
• proton particle ID (dE/dx) improves S/B

Fitted signal (65 pb-1) Now 36128 with 195
pb-1
Cleaner with PID !
Measure
New Result ! (based on 65 pb-1)
BR(Lb ? Lc p?) (6.0 ?1.0(stat) ? 0.8(sys) ?
2.1(BR) ) x 10-3
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More BaryonsFirst observation of X0c, Xc
p
X0c
X-
Xc
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Run II Results
Bs?Ds-?

• - Bs ?Ds-? is the golden mode for measuring xs.
• - Fully reconstructed mode for minimal
  uncertainty in the boost of the Bs.

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B?hh?

• m 5.252(2) GeV/c2
• ? 41.1(1.9) MeV/c2

Simulation
Fitted contributions
Bd?K? Bs?KK Bd?? ? Bs?K ?
mode Yield (65 pb-1)
B0?K? 148?17(stat.)?17(syst)
B0??? 39?14(stat.)?17(syst)
Bs?KK 90?17(stat.) ?17(syst)
Bs?K? 3?11(stat.) ?17(syst)
M(??)
First observation of Bs?KK? !! Result Measure
ACP
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Unfolding two body decays

• Unfolding
• Kinematics (momentum ratio)
• Mpp vs q1(1-p1/p2)
• Different correlations for various species/decay
  channel
• dE/dx in Central Tracker

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Latest B-gthh BR direct ACP
Bd??? 160 ? 27
Bs?KK 225 ? 29
Bs?K? 28 ? 25
Bd?K? 542 ? 30
Very preliminary
ACP(Bd?K?) -0.08 ? 0.07

• Substantial yields in 180pb-1
• Bd yields 80fb-1 Babar
• RAW yields for the moment
• Update of LP03 result at ICHEP04

• Direct Acp(Kp) to 7 (Babar 5_at_same yield)
• BR(Bs?KK) to 15 -gt Constraints CKM (angle ?)
• Largest fully reconstructed Bs sample, CP
  eigenstate ? ??s

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B?hh expectations
CDF 180 pb-1
Current single best measurement
Scaling from current yields
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B ? ?K
BR

• Pure-penguin, b-gtsss decay
• Sensitive to Vts and NP
• BR direct-ACP (180pb-1)

ACP
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First Observation of Bs ? ff
Good S/B !
5? significance
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B Flavor Tagging
OST (opposite side tagging) Bs produced in
pairs ? tag flavor of opposite B
JETQ sign of the weighted average charge
of opposite B-Jet SLT sign of soft lepton
from decay of opposite B

• SST (same side tagging)
• B0 (B0) is likely to be accompanied by a ? (??)
• Search for the track with minimum PTREL

Kaon taggers (new in CDF) OST (K from b?c?s
transition) SST (K from fragmentation)

• Evaluation in progress, expectations between
  5-10
• Learning process in runII no faster than
  runI...

simpler algorithm
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First Bd mixing results

• CDF Same Side Tagging
• Exclusive samples
• D0 m tagging
• Semileptonic sample

CDF
D0
?md0.506?0.055(stat)?0.049(syst) ps-1
Tagging efficiency 4.8 /- 0.2 Tagging
purity 73.0 /- 2.1 (D 0.46)
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Hadronic Yields for Bs mixing

• Currently 1.5pb of hadronic 1pb needing
  reflection cleanup

BR paper draft
Need 2pb and ?D2 5 for 5? sensitivity up to
24ps-1 in 3.2 fb-1

• - xs is the most complex of all
• B measurement
• Need to combine many ingredients

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Bs mixing reach

• Assumptions
• Yield
• 2k ev./fb-1
• From data
• Flavor Tagging
• eD2 5
• Pessimistic
• Needs work
• Time resolution
• 50 fs
• Need L00
• Signal/Noise
• 2/1
• Data is better

Go beyond SM preferred range 5s measurement if
Dms 18 ps-1 with 1.7 fb-1 5s measurement if Dms
24 ps-1 with 3.2 fb-1
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Conclusions

• Tevatron is finally delivering luminosity
• Experiments are accumulating data of excellent
  quality
• D0 is in business thanks to new magnetic tracking
• CDFs secondary vertex trigger is a major success
• Wealth of new results from fully hadronic decays
  promises a very interesting future!
• Analyses involving flavor tagging are starting
  now and still need optimization of the basic
  tools
• Results on Bs mixing and g require statistics at
  the fb-1 level. This will take at least until
  2005

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Backup slides
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Semileptonic samples

• CDF/D0 have large samples
• Lifetimes need refinement of systematics
• Mixing measurements will follow

Bs
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D cross section

• Get prompt charm fraction from study of D impact
  parameter
• Fprompt 80-90 varies with D species

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D meson signals
D0?Kp

• Huge D samples sraw 10 nb
• Use D?Dps for cleanup
• ps gives sign of kaon Dm
• Measure BR of suppressed 2 body decays to PDG
  accuracy
• Measure CP asymmetries

D0?pp ACP21.70.6
D0?KK ACP31.90.6
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b-decay Bs mixing (prospects)

• Signal (N)
• Need all charged hadronic mode for resolution and
  statistics ? secondary vertex trigger is
  essential
• Bs ? Ds p?, Ds 3p ?
• Ds ? f p, K0 K, K0S K
• Expectations for Run IIA in 2 fb-1
• 20,000 events (P-909)
• 75,000 Yellow Book
• Realistic 7,000
• S/B
• 11 from Run I extrapolations
• Assume 12 21 range
• Small effect on significance

CDF preliminary Run II data
Few pb-1
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b-decay CP violation

• As usual one measures
• Aobs(t) D ACP(t) D sin(2b) sin(Dmdt)
• Important to calibrate dilution with mixing
  analyses
• Typical CP eigenstates have small Branching
  Ratios 10-5!
• Large b x-section at Tevatron is very useful
• CDF Run 1 measurement is not competitive with
  B-factories, but it is very useful to estimate
  our future capabilities in Run II

Measurements of sin(2b) PDG 2003
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b-decay CP violation

• CDF Run 1 result is based on
• 400 B0 ? J/y K0S
• All available taggers
• Opposite side lepton, Jet-charge
• Same side pion charge correlation
• Result

400 B ? y K0S
Asymmetry Vs. lifetime
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b-decay CP violation (prospects)

• Extrapolation based on analytic formula for the
  error on the time integrated asymmetry
• In addition we account for improvements made by
  studying the time evolution
• Expectations in 2 fb-1

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D0?mm

• Rare decay D0?mm
• SM 3x10-13
• R-violating SUSY 3.4x10-6
• Best so far 4.1x10-6
• Beatrice/E771
• CDF limit 2.5 (3.3)x10-6 _at_ 90 (95) CL
• Luminosity used 63.5 pb-1
• Method
• Yield of D? D0 p ? mm p relative to D? D0 p
  ? ppp
• 1x10-7 by end of run II

Phys. Rev. D68, 091101 (2003)