1. Flavor Physics at the Tevatron
Franco Bedeschi
INFN - Sezione di Pisa
LNF: May 2004
F. Bedeschi, INFN-Pisa

2. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

3. 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 <ŝ>
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
0.2 at B-factories, 0.14 at LEP
LNF: May 2004
F. Bedeschi, INFN-Pisa

4. HF at the Tevatron Production more complex than in e+e- NLO LO
s, t, u-channel and NLO~LO
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
LNF: May 2004
F. Bedeschi, INFN-Pisa

5. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

6. 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+
LNF: May 2004
F. Bedeschi, INFN-Pisa

7. Run 1 Successful B physics program at Tevatron during run 1
Lifetimes
First evidence of sin(2b)
Mixing
Integrated luminosity ~ 120 pb-1
LNF: May 2004
F. Bedeschi, INFN-Pisa

8. Run II: Tevatron 8.6 fb-1 4.4 fb-1 Base plan ~ no recycler
Peak luminosity:
7x1031
Delivered/on tape:
500/400 pb-1
Analyses based on
~ 240 pb-1 > 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

9. The Upgraded CDF Detector
Central calorimeters
Solenoid
Central muon
New
Old
Partially
new
Front end
Trigger
DAQ
Offline
TOF
Endplug
calorimeter
Silicon and drift chamber trackers
Forward muon
LNF: May 2004
F. Bedeschi, INFN-Pisa

10. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

11. 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 %
J/Y  m+ m-, e+ e- 6% each
Secondary vertex!:
ctD & ctB ~ mm
Only way for had. decays
l - n b W- B c D q D q B b q c W- s
J/Y K
Tracks from
underlying event
B decay
b fragmentation
Primary
vertex
B/D meson
LNF: May 2004
F. Bedeschi, INFN-Pisa

12. CDF SVT trigger Need dedicated impact parameter trigger Resolution
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
s=48 mm
80%
LNF: May 2004
F. Bedeschi, INFN-Pisa

13. PID at CDF Time of Flight dE/dx in COT and SVX K p K  1.5 GeV/c
TOF: >1 K/π separation up to p=2 GeV
dE/dx in COT
K/π sep.
(was 1.2)
Controllare ultimo update del dedx di Diego
Aggiungere cifre sul tracking resulution
1.5 GeV/c
dEdx in Silicon Vertex for low-pt tracks
PLAN: combine them all !
LNF: May 2004
F. Bedeschi, INFN-Pisa

14. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

15. X (3872) Search for Xyp+p- FERMILAB-PUB-03/393-E
Confirm signal from Belle
FERMILAB-PUB-03/393-E
X yield: 730 ± 90 cand. (11.6 s)
Y(2S)
M = ±0.7± 0.4 MeV
m(pp) > 500 MeV
hep-ex/
LNF: May 2004
F. Bedeschi, INFN-Pisa

16. Rare decays: Bd(s)  m+m-
1.9  10-7
7.5  10-7
BR C.L.
1.5  10-7
5.8  10-7
BR C.L.
1.07±0.31
1.05±0.30
Background 1
Data
Bd  m+m-
Bs  m+m-
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 Pt> GeV, |eta|<0.6
“Blind” analysis: cuts optimized
before looking at the signal region
1.6  10-7
2.0  10-7
LNF: May 2004
F. Bedeschi, INFN-Pisa

17. Bs  m+m- implications for SUSY
R. Arnowitt et al.,
PLB 538 (2002) 121,
new plot by B.Dutta
R. Dermisek et al.,
hep-ph/
7.510-7
SO(10)
R-parity violating
New limit excludes significant amounts of the previously allowed SUSY models parameters - Expect ~10-7 with 1fb-1
LNF: May 2004
F. Bedeschi, INFN-Pisa

18. Run II Results Precision mass measurements:
M(Bu) = ±0.41±0.34 MeV/c2
M(Bd) = ±0.53±0.30 MeV/c2
M(Bs) = ±0.73±0.30 MeV/c2
M(Lb) = ± 1.2 ± 1.2 MeV/c2
Current world best values
LNF: May 2004
F. Bedeschi, INFN-Pisa

19. Run II Results CDF Lifetimes measurements:
D0 has best measurement of ratio of Bu and Bd lifetimes:
t(Bu)/t(Bd) = 1.093±0.021±0.022
(CDF:
Bu/Bd =  0.042
Bs/Bd =  0.072)
Consistent and only slightly worse than BaBar PDG result
New technique used fitting the ratio of lifetime distributions in semileptonic decays
LNF: May 2004
F. Bedeschi, INFN-Pisa

20. Run II Results D0 lifetime ratio determination:
m-D*+X: mostly Bd
m-D0X: mostly Bu
Fit ratio r=N(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
LNF: May 2004
F. Bedeschi, INFN-Pisa

21. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

22. Run II Results
Polarization analysis consistent with B factories for BdJ/y K*0
Best measurement for Bs  J/y f
Important step toward DGs
A0, A// are CP-even ~ 75%
BdJ/K*
LNF: May 2004
F. Bedeschi, INFN-Pisa

23. The Bc, rediscovered… CDF Run1
Box still closed for blind analysis of J/y p
(10% of J/y ln)
LNF: May 2004
F. Bedeschi, INFN-Pisa

24. 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 BR’s and integrated CP asymmetries
Basic samples for future g measurements
LNF: May 2004
F. Bedeschi, INFN-Pisa

25. 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)= 3.608±0.054(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 Kp KK
LNF: May 2004
F. Bedeschi, INFN-Pisa

26. Run II Results
Now going for BR and ACP of D+ πππ - No experiment ever had >1500 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 !
LNF: May 2004
F. Bedeschi, INFN-Pisa

27. Run II Results BdD-+ - MC templates used to fit mass spectrum.
- B DK is another mode of interest for CP analysis.
LNF: May 2004
F. Bedeschi, INFN-Pisa

28. bc with cpK New Result ! (based on 65 pb-1) Cleaner with PID !
Backgrounds: real B decays
Reconstruct p as p: Bd  Dp+K+p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 361±28 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

29. More Baryons: First observation of X0c, X+cp
X0c X-
X+c
LNF: May 2004
F. Bedeschi, INFN-Pisa

30. 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.
LNF: May 2004
F. Bedeschi, INFN-Pisa

31. Bh+h Fitted contributions: M() mode Yield (65 pb-1) B0K
m = 5.252(2) GeV/c2
 = 41.1(1.9) MeV/c2
kinematics & dE/dx to separate contributions
Simulation
BdK
BsKK
Bd 
BsK 
Fitted contributions:
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K+K !!
Result:
Measure ACP
Concerning the signal extraction, Bhh events are collect by the SVT trigger
Requiring the two tracks be displaced and with a relatively large opening angle to
Reduce the QCD combinatorial background.
After optimization of the cut a clean signal peak of about 300 events is visible in the
Pi-pi invariant mass spectrum, due to the superposition of the different B0 and Bs
Decay modes, with a good agreement with the results of the simulation.
The issue is then to be able to separate these contributions.
LNF: May 2004
F. Bedeschi, INFN-Pisa

32. Unfolding two body decays
Kinematics (momentum ratio)
Mpp vs q1*(1-p1/p2)
Different correlations for various species/decay channel
dE/dx in Central Tracker
LNF: May 2004
F. Bedeschi, INFN-Pisa

33. Latest B->hh BR& direct ACP
Bd = 160  27
BsKK = 225  29
BdK = 542  30
BsK = 28  25
Very preliminary
ACP(BdK) =  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(Kπ) to 7% (Babar yield)
BR(BsKK) to 15% -> Constraints CKM (angle )
Largest fully reconstructed Bs sample, CP eigenstate  s
LNF: May 2004
F. Bedeschi, INFN-Pisa

34. Current single best measurement
Bhh expectations
CDF 180 pb-1
Current single best measurement
Scaling from current yields
LNF: May 2004
F. Bedeschi, INFN-Pisa

35. B+  K+ BR Pure-penguin, b->sss decay Sensitive to Vts and NP
BR & direct-ACP (180pb-1) BR
ACP
LNF: May 2004
F. Bedeschi, INFN-Pisa

36. First Observation of Bs  ff
Another B->sss penguin process
QCDF expectation:
Good S/B !
5 significance
LNF: May 2004
F. Bedeschi, INFN-Pisa

37. B Flavor Tagging OST (opposite side tagging):
B’s 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)
N/A
in progress
Same side kaon
2.2  1.3
0.4  0.02 *
Jet charge
Opp. side kaon
2.1  0.5
1.0  0.5
Same Side
e+µ 2.10.5
Soft electron
0.7  0.2
Soft muon
CDF-I
CDF-II
D2 [%]
Verificare situazione di tagging
Evaluation in progress, expectations between 5-10%
Learning process in runII no faster than runI...
*simpler algorithm
LNF: May 2004
F. Bedeschi, INFN-Pisa

38. First Bd mixing results
CDF: Same Side Tagging
Exclusive samples
D0: m tagging
Semileptonic sample
CDF D0
md=0.5060.055(stat)0.049(syst) ps-1
Tagging efficiency: /- 0.2 %
Tagging purity: /- 2.1 % (D = 0.46)
LNF: May 2004
F. Bedeschi, INFN-Pisa

39. 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

40. Bs mixing reach Assumptions Go beyond SM preferred range:
Dms (ps-1)
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
LNF: May 2004
F. Bedeschi, INFN-Pisa

41. Conclusions Tevatron is finally delivering luminosity
Experiments are accumulating data of excellent quality
D0 is in business thanks to new magnetic tracking
CDF’s 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

42. Backup slides
LNF: May 2004
F. Bedeschi, INFN-Pisa

43. Semileptonic samples CDF/D0 have large samples:
Lifetimes need refinement of systematics
Mixing measurements will follow Bs
LNF: May 2004
F. Bedeschi, INFN-Pisa

44. D cross section
Get prompt charm fraction from study of D impact parameter
Fprompt ~ % varies with D species
LNF: May 2004
F. Bedeschi, INFN-Pisa

45. D meson signals Huge D samples: sraw ~ 10 nb D0Kp
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
ACP=2±1.7±0.6 %
D0KK
ACP=3±1.9±0.6 %
LNF: May 2004
F. Bedeschi, INFN-Pisa

46. 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 
D+s  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:
~ 1:1 from Run I extrapolations
Assume 1:2 – 2:1 range
Small effect on significance
CDF preliminary
Run II data
Few
pb-1
LNF: May 2004
F. Bedeschi, INFN-Pisa

47. 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 Ratio’s ~ 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
LNF: May 2004
F. Bedeschi, INFN-Pisa

48. b-decay: CP violation CDF Run 1 result is based on: Result:
~ 400 B0  J/y K0S
All available taggers:
Opposite side: lepton, Jet-charge
Same side: pion charge correlation
Result:
~ 400
B  y K0S
sin(2b) = 0.91
+ 0.37
- 0.36
Asymmetry
Vs. lifetime
LNF: May 2004
F. Bedeschi, INFN-Pisa

49. 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: N B D 1 x ) (2
sin ( 2 d + e b
LNF: May 2004
F. Bedeschi, INFN-Pisa

50. D0mm Rare decay D0mm CDF limit: 2.5 (3.3)x10-6 @ 90 (95)% CL
SM: ~ 3x10-13
R-violating SUSY: 3.4x10-6
Best so far: 4.1x10-6
Beatrice/E771
CDF limit: (95)% CL
Luminosity used 63.5 pb-1
Method:
Yield of D+* D0 p  [mm] p relative to D+* D0 p  [pp]p
~ 1x10-7 by end of run II
Phys. Rev. D68, (2003)
LNF: May 2004
F. Bedeschi, INFN-Pisa