B masses, lifetimes and mixing at the Tevatron

1
B masses, lifetimes and mixing at the Tevatron
XXXXth Rencontres de Moriond La Thuile, March
12-19 2005      Franco Bedeschi INFN-Pisa
OUTLINE

• Tevatron and Detectors
• Data sets
• Masses
• Lifetimes
• Mixing

2
Data sets

• CDF/D0 use data collected in the period 2002-2004
• 600 pb-1 recorded
• D0
• 220-450 pb-1 used for B physics
• CDF
• 240-360 pb-1 used for B physics
• Lost 100 pb-1 due to Central Tracking Chamber
  ageing problem
• Now completely resolved

3
Data samples

• J/y samples
• Millions! 20 are from Bs
• Reconstruct exclusive B/LB?J/y K/L0 modes
• Semi-leptonic B ? D ln X samples
• 100 K events with fully reconstructed D
• D0 has larger muon acceptance
• CDF lowers lepton trigger pt by requiring
  additional displaced track
• Fully hadronic decays (CDF only)
• 10 K events fully reconstructed Bs
• Requires trigger on secondary vertex (SVT)

4
B hadron lifetimes

• B hadron decays dominated by b-quark decay
• Effect of spectator quarks can be included with
  perturbative expansions in terms of 1/mb (HQE)
• Expect small differences between lifetimes of
  different species
• Non-perturbative ME from lattice, Wilson coeff.
  from perturbative QCD
• NLO improves agreement
• Ratios reduce theory uncertainties

C. Tarantino, hep-ph/0310241 October 2003
LO
NLO
Experiment
Theory
5
Lifetimes

• HFAG 2004 averages as of summer 04
  (hep-ex/0412073 Jan. 2005)
• B0, B dominated by BaBar/Belle (latest not yet
  included in HFAG average)
• Best result from Belle ? calibration result for
  Tevatron measurements ?
• B0 1.5340.0080.010, B 1.6350.0110.011,
  t(B)/t(B0)1.0660.0080.008
• Bs, LB dominated by CDF/D0, LEP
• t(B)/t(B0) No Tevatron Run II results included
• Bs Includes Run II D0 J/yf (220 pb-1), CDF J/yf
  (240 pb-1)
• See talk by S. Burdin for new DGs/Gs measurements
• LB Includes Run II D0 J/yL (250 pb-1), CDF J/yL
  (65 pb-1)

b hadron species average lifetime t/t(B0) measurement t/t(B0) Theory 2004 () (NLO)
B0 1.534 0.013 ps
B 1.653 0.014 ps 1.081 0.015 1.060.02
Bs 1.469 0.059 ps 0.958 0.039 1.000.01
LB 1.232 0.072 ps (0.803 0.047) 0.860.05
() Gabbiani et al., hep-ph/0407004 Oct.2004
6
Lifetimes with B?lnDX modes

• Highest statistics samples
• Difficult systematics
• Sample composition for Bu, Bd
• Cross talk from D, D
• Backgrounds
• Combinatorial
• Physical B?D()D()
• Prompt c-cbar, b-bbar, Dfake
• Recent result from CDF with low statistics lepton
  pt gt 8 GeV sample
• t(B) 1.6530.0290.032 ps, t(B0)
  1.4730.0360.054 ps
• t(B)/t(B0) 1.1230.0400.040
• Very high statistics secondary vertex triggered
  sample still under study

7
Lifetime ratio with B?lnDX modes

• D0 new method to determine t(B)/t(B0)
• Fit the ratio of the lifetime distributions
• Many systematics are reduced in the ratio
• Best measurement of this ratio at Tevatron
• t(B)/t(B0) 1.080.0160.014

126,000 D0
8
Lifetimes with Bs?lnDsX modes

• First high statistics Bs lifetime measurement
  from D0
• Use Ds ? fp decay
• Difficult background systematics
• Combinatorial
• Physical B?D()D()
• Prompt c-cbar, b-bbar, Dfake
• Currently best measurement
• t(Bs) 1.4200.0430.057 ps

NDs 5153
Systematics Summary (mm)
9
Lifetime with hadronic decays

• CDF
• First measurement with Secondary Vertex Trigger
  biased samples
• Trigger/analysis ct-efficiency curves from
  realistic MC
• Check by emulating trigger cuts on B? J/y K
• Use several final states
• B D0p 8380 ev. (D0?Kp)
• B0 Dp? 5280 ev. (D?Kpp)
• D 3p 4173 ev. (D?Kpp)
• Bs Ds p 465 ev. (Ds?fp)
• Ds 3p 133 ev. (Ds?fp)
• Important for Dms measurement

10
Lifetimes with hadronic decays

• More statistical power than J/y modes
• Slightly larger systematics
• Efficiency curve
• backgrounds

Bs
B
t(B) 1.6610.0270.013 ps t(B0)
1.5110.0230.013 ps t(Bs) 1.5980.0970.017 ps
Systematics (mm)
Bs
B
11
Lifetimes new results summary

• Many new results not included in HFAG 2004
  averages
• To come
• CDF high statistics semi-leptonic results
• Ratios in several modes
• Updates on LB

 Lum. CDF y modes D0 y modes CDF hadronic CDF semi-leptonic (Hi pt) D0 semi-leptonic (y) HFAG
pb-1 240 220 (250) 360 260 400 2004
B0 1.5390.0510.008 1.4730.0510.023 1.5110.0230.013 1.4730.0360.054   1.534 0.013
B 1.6620.0330.008 1.6610.0270.013 1.6530.0290.032   1.653 0.014
B/B0 1.080.042   1.1230.0400.040 1.080.0160.014 1.081 0.015
Bs 1.3690.1000.009 1.4440.0940.020 1.5980.0970.017   1.4200.0430.057 1.469 0.059
Bs/B0 0.8900.072 0.9800.0730.003       0.958 0.039
LB   (1.220.200.04)       1.232 0.072
Included in HFAG averages
Red Very recent! Just approved
12
B mixing

• Neutral Bs mix
• SM interpretation with box diagrams
• Frequency Dmd,s ? Vtd,s2
• Constraints to CKM weak due to theory
  uncertainties
• Theory accuracy 5 in ratio Dmd/Dms
• Bd mixing measured and established clearly
• LEP, CDF-1, CDF-2, D0-2, BaBar, Belle
• Bs mixing not observed
• Limits set by LEP, SLD, CDF-1

13
B mixing

• Basic ingredients for the measurement
• High statistics samples of neutral Bs in flavor
  specific decays
• CDF J/yK, Dp, lnDX
• D0 J/yK, lnDX
• Proper decay length reconstruction
• Fully reconstructed modes provide better accuracy
• Tagging of flavor at production (flavor tagging)
• Key problem at the Tevatron!
• Equivalent statistical power N eD2
• e tagger efficiency
• D tagger dilution 2h-1 (h probability of
  correct tag)
• Measure A(t) (Nnm-Nm)/ N D cos(Dm t)
• Nnm (Nm) number of Bs with same (different)
  flavor at production and decay
• Mixing measurement calibrates dilution
• Impossible for Bs until oscillation observed

14
Bd Mixing

• HFAG Summary Based on result presented in summer
  2004
• World Average dominated by BaBar/Belle

15
Flavor tagging
Signal side

• Opposite side techniques (OST)
• CDF total eD2 1.1 1.4
• Soft Muon Tag
• Soft Electron Tag
• Jet Charge Tag
• D0 eD2 1.1
• Enhanced muon tag eD2 1.1
• Add-in correlations with associated jet in
  likelihood
• Same side techniques (SST)
• Sign of nearby track is correlated to b type
  (SST)
• Tagging power depends on B type
• PID helps for Bs
• eD2 1 for CDFD0 in Bd

Opposite side B
16
Bd mixing

• 2 recent results from CDF using 355 pb-1 and OST
• Semi-leptonic sample 124k lD0 (24k lD), 53k
  lD
• Dmd 0.497 0.028(stat.) 0.015(syst.) ps-1
• Hadronic sample 5.3k yK, 2.2k yK, 6.2k D0p-,
  5.6k D-p
• Dmd 0.503 0.063(stat.) 0.015(syst.) ps-1

Average all taggers
17
Bd Mixing

• These results obtained using many features
  important for Bs mixing
• Unbinned fit
• Parametrized dilutions
• Calibrate dilutions
• Test amplitude scan on fully reconstructed Bd
• Fit DAcos(Dm t) at fixed Dm
• Expect A1 for Dm Dmd
• Limit (95 CL)
• Dm such that A1.645sA 1
• Sensitivity Dm such that 1.645sA 1

  CDF had CDF semi D0 semi
Tagger
OST m 0.46 0.50 1.07
OST e 0.18 0.28  
OST jet 0.49 0.61  
Total OST 1.130.18 1.380.10 1.07
Limit
Sensitivity
H. G. Moser, A. Roussarie, NIM A384 (1997)
18
Bs mixing
SM Fit (2004) Dms 18.3 1.6 ps-1

• Tevatron experiments do not have yet sensitivity
  for observation of SM prediction
• New results
• CDF
• Limit with combined fully reconstructed and
  semi-leptonic modes (this talk)
• D0
• Limit with semi-leptonic modes (S. Burdin talk)

19
CDF Bs mixing (signals)
?hadronic peaks ?semi peaks

• Hadronic analysis Bs?Dsp
• 900 events
• Cross-check with hadronic lifetime analysis
  (independent group)
• Semi-leptonic analysis Bs?Dsln
• 7.5k events
• Cross-check with parallel independent analysis

Channel Yield S/B
BsDsp (Dsfp) 52633 1.80
BsDsp (DsKK) 25421 1.69
BsDsp (Ds3p) 11618 1.01
BsDsln (Dsfp) 435594 3.12
BsDsln (DsKK) 175083 0.42
BsDsln (Ds3p) 157388 0.32
Right sign
Wrong sign
20
CDF Bs mixing (cross-checks)

• Details (K-f)
• (ct-eff)
• (sct-SF)
• t (had, lD)

• Mass and lifetime projections
• Mass and lifetime consistent with World Avg.
  values/D0

tBs 1.5180.090
Ds?fp
21
CDF Bs Mixing (scans-1)

• Amplitude scans all statistics dominated

Semi-leptonic
Hadronic
22
CDF Bs mixing (scans-2)
?Old projections

• Combined scan results
• 7.9 ps-1 95 CL limit
• Sensitivity 8.4 ps-1
• Effect on World Average
• Limit 14.5 ? 14.5 ps-1
• Sensitivity 18.2 ? 18.6 ps-1

CDF Run 1 limit
23
Conclusions

• Many new results from the Tevatron
• Major new results in Bs sector
• More Bs results from D0 (talk by S. Burdin)
• Lifetime updated and more to come
• First CDF/D0 Bs mixing limits
• Lower than expectations
• Additional improvements could reduce the
  statistical error on the amplitude by up to a
  factor two with same data set
• It is a very difficult analysis, but now we are
  in business

24
Backup
Backup Slides
25
Tevatron

• Tevatron is delivering good luminosity consistent
  with 2002 predictions
• 750 pb-1 delivered per experiment since start
  of Run II
• Peak luminosity in excess of 1032 ? Best 1.1x1032
• Injections around 1032 are now rather common
  occurrence
• Good Recycler performance

26
Detectors

• CDF
• Excellent mass resolution
• Particle ID dE/dx, TOF
• Tracking triggers (Hadronic Bs)
• L1 Tracks
• L2 Secondary vertex

• D0
• Excellent muon and tracking coverage
• Tracking up to hlt3
• Muons up to hlt2

27
Masses

• D0
• Old 04 results
• Narrow B resonances
• B--gt narrow D sates (D1, D2)
• Bc meson in semileptonic decays
• New winter 05 results
• Ds states

• CDF
• Old 04 results
• D Ds mass difference
• D states D1, D2
• B meson masses
• New winter 05 results
• Hadronic Bc
• B fits (PR plot)

28
B hadron masses

• B mass determination
• Use clean J/yK modes
• Accurate tuning of momentum scale with large J/y
  sample

CDF
CDF
D0
D0
29
Masses

• Run II results or better of current world
  averages
• CDF has best results due to better tracking
  resolution
• Close to being systematics dominated

B hadron species Mass (MeV/c2) CDF Run II (2004) Mass (MeV/c2) PDG 2004 average PDG Reference
B 5279.1 0.41 0.36 5279.1 0.5 CLEO2 (00), CDF(96)
B0 5279.6 0.53 0.33 5279.3 0.7 CLEO2 (00), CDF(96)
Bs 5366.0 0.73 0.33 5369.6 2.4 CDF(96), LEP
LB 5619.7 1.2 1.2 5624 9 CDF(97), LEP
Bc See next talk by M.Corcoran 6400 390 130 6320 60 CDF(98) - Semileptonic OPAL(98) - J/yp
30
X (3872)

• CDF (11.6s) and D0 (5.2s) confirm X (3872)
  observations from the B factories
• CDF measures large prompt fraction
• fB(X) 16.14.92.0
• fB(y(2S)) 28.31.00.7

31
Masses

• Many results not covered in this talk
• Charmless two body decays ? link
• Bc in fully and partially reconstructed modes
  (next talk)
• Measurements of D and B narrow resonances ?
  link
• Pentaquark searches ? link
• Charmed baryons ? link

32
B? hh
? back

• Several new results based on this sample
  presented at ICHEP last summer
• Branching fractions
• Integrated CP asymmetries

33
B?hh
? back

• Branching ratios and CP asymmetry

• Rare two body decay modes

34
B?fh
? back

• CDF B? fK
• ACP -0.07 0.17 0.05
• (BaBar 0.054 0.056 0.012)
• BR(B? fK) (7.2 1.3 0.7)x10-6
• (HFAG (9.0 0.7)x10-6)
• CDF Bs? ff
• BR(Bs?ff) (1.4 0.6 0.2 0.5(norm))x10-5
• (QCD fact. 3.68x10-5)
• (NF fact. 1.79x10-5)

First observation!
35
D mesons
? back

• CDF Mass and width
• D0 B.R.

4
G?300MeV
Belle hep-ex/0307021
36
B mesons
? back

• D0
• First high statistics observation
• CDF
• Preliminary results consistent with D0

37
Pentaquark searches
? back

• Pentaquark signal searched by CDF
• No evidence observed so far
• Set limits on production cross-section

38
Charm baryons
? back

• Charm baryons observed for first time at p p-bar
  collider by CDF

39
Lifetimes
? back

• CDF
• Old 04 results
• Bs/Bd polarization and lifetime difference
• Exclusive psiK lifetimes Bu/Bd lifetime ratio
• New winter 05 results
• Lifetimes from semileptonic 8 GeV data
• Lifetimes from hadronic modes

• D0
• Old 04 results
• Bs lifetime from psi phi mode (Bs/B0)
• Bd/Bu lifetime ratio
• New winter 05 results
• DGs/Gs results and polarization studies
• Bs lifetime using DslvX

40
Lifetimes with J/y K modes

• Cleanest channels, but statistics limited
• Best Tevatron results from CDF (240 pb-1)
• B? yK, B0? yK, K0S, Bs?yf
• Main background from prompt y tracks
• No kinematic uncertainty
• Systematics at level of B factories
• t(B) 1.6620.0330.008, t(B0)
  1.5390.0510.008
• t(Bs) 1.3690.1000.009

NBs 256
41
Mixing

• CDF
• Old 04 results
• B0 oscillations with SST in fully reconstructed
  decays
• B0 oscillations with OST in semileptonic decays
• B0 oscillation with SST in semileptonic decays
• New winter 05 results
• B0 mixing with OST in hadronic decays
• B0 mixing with OST in semileptonic decays
• Bs mixing with OST in hadronic decays
• Bs mixing with OST in semileptonic decays

• D0
• Old 04 results
• B0 oscillation with OS mu tag
• B0 oscillation with SS tag
• B0 oscillation with OS mu tag, Jet Charge and SST
• New winter 05 results
• Dms limit from semileptonic decays

42
CDF Bs signals
? back
3p
Hadronic samples
Wide range
Fit projection
KK
43
CDF Bs signalssemi-leptonic samples
? back
3p
KK
44
CDF Bs? lnDs k-factors
? back

• K-factor pt(lD)/pt(B)
• Binned by M(lD)

Ds?KK
Ds?ppp
Ds?fp
45
CDF Bs ct-efficiencies
? back

• Semi-leptonic sample
• All ct efficiencies obtained with realistic MC
• Cross check lifetimes consistent with D0/WA

Ds?ppp
Ds?fp
Ds?KK
46
CDF Bs ct-efficiencies
? back

• Hadronic sample
• All ct efficiencies obtained with realistic MC
• Cross check lifetimes consistent with D0/WA

Ds?fp
Ds?KK
Ds?ppp
47
CDF Bs lifetime checkssemi-leptonic sample
? back

• Raw lifetimes from mixing fit not good for
  averaging
• Average tB 1.4770.032 ps no systematics
  evaluated
• D0 t(Bs) 1.4200.0430.057 ps, WA t(Bs)
  1.469 0.059 ps

tBs 1.4100.086
tBs 1.3810.067
tBs 1.5210.040
Ds?ppp
Ds?fp
Ds?KK
48
CDF Bs lifetime checkshadronic sample
? back

• Raw lifetimes from mixing fit not good for
  averaging
• Average tB 1.5150.070 ps no systematics
  evaluated
• D0 t(Bs) 1.4200.0430.057 ps, WA t(Bs)
  1.469 0.059 ps

tB 1.3770.186
tB 1.5500.131
Ds?ppp
Ds?KK
49
CDF Bs s(ct) scale factors
? back

• s(ct) scale factor distributions in
  semi-leptonic sample
• Calculation from large data control sample
• Parameterization in terms of many variables

Ds?ppp
Ds?fp
Ds?KK
50
CDF Bs s(ct) scale factors
? back

• s(ct) scale factor distributions in the hadronic
  sample
• Calculation from large data control sample
• Parameterization in terms of many variables

Ds?ppp
Ds?fp
Ds?KK
51
Old Sensitivity Plots
? scan ?conclusions

• Recall ICHEP August 2004 predictions (statistical
  only!)

?ms14 ps-1
?ms23 ps-1
52
Future Mixing Improvements
? back

• Include Same Side (Kaon) Tagging
• Expect twice tagging power than OST combined
• Improve accuracy of primary vertex
• Add more channels
• Bs?Ds3p
• Bs?Dsp, Bs?Dsr
• Partial reconstruction can treat as semi-leptonic
  case