1. B Physics at the Tevatron
Primarily in this talk: Physics of the Bs Meson
Matthew Herndon, University of Wisconsin Madison
10-25 years of DØ(Tevatron) France

2. Physics of the Bs Meson Introduction The Bs Meson More Bs Mesons
Lifetimes and 
Direct CP Violation
Bs Oscillations
CP Violation in BsJ/
Conclusions

3. Look for new physics that could explain these mysteries
If Not the SM What?
Standard Model predictions validated to high precision, however
Standard Model fails to answer many fundamental questions
Gravity not a part of the SM
What is the very high energy behaviour?
At the beginning of the universe?
Grand unification of forces?
Dark Matter?
Astronomical observations of indicate that there is more matter than we see
Where is the Antimatter?
Why is the observed universe mostly matter?
Look for new physics that could explain these mysteries
Look at weak processes which have often been the most unusual: B Physics!

4. Bs Mesons d b s b 79 GHz Very interesting right from the start.
The Bs known about since UA1 experiment in 1987.
Could infer the existence of a very fast oscillating meson
SS vs OS leptons
New physics and the Bs Meson
One example: Higgs couples to mass, heavier mesons of interest
Investigate
Spectroscopy
Rare Decays
Lifetime and 
Oscillations
CP Violation
very fast b s Z'
Many new physics possibilities!

5. The Tevatron Run 2 1.96TeV pp collider CDF/DØ Integrated Luminosity
Excellent performance and improving each year
Record peak luminosity in 2008: 3.2x1032sec-1cm-2
Run 1 worth of data every few weeks
CDF/DØ Integrated Luminosity
~5fb-1 integrated, 3fb-1 analyzed
All critical systems operating including silicon
Added ~2fb-1 in 2008
Bs physics benefits from more data

6. CDF and DØ Detectors CDF Tracker Triggered Muons and SVT: |η|<1.0
Silicon |η|<2, 90cm long, rL00 = cm
96 layer drift chamber 44 to 132cm
Triggered Muons and SVT: |η|<1.0
EXCELLENT TRACKING: MASS RESOLUTION
EXCELLENT TRACKING:
TIME RESOLUTION
DØ Tracker
Silicon and Scintillating Fiber
Tracking to |η|<2
New L0 on beam pipe
Triggered Muon coverage: |η|<2.0
EXCELLENT TRACKING: EFFICIENCY

7. The Triggers Hadron collider: Large production rates
σ(pp → bX, |y| < 1.0, pT(B) > 6.0GeV/c) = ~30μb, ~10μb
Backgrounds: > 3 orders of magnitude higher: ~100 mb
Single and double muon based triggers and displaced track triggers
TRIGGERS ARE CRITICAL
Billions of B and Charm Events on Tape

8. Orbitally Excited Bs**
Excited Bs states
B+ sample selected using NN
58,000 Events, then add Kaons
94.8  23.4
Bs2*
36.4  9.0
Bs1
> 5s significance
Masses
10.20  0.44  0.35 MeV/c2
m(Bs2*)-m(Bs1)
 0.2  0.6 MeV/c2
m(Bs1)
Other Tevatron discoveries: Bc(CDF,DØ), b(CDF), b(CDF,DØ), b(DØ)

9. Bs Lifetime and 
 Bs Width-lifetime difference between eigenstantes
Bs,Short,Light  CP even Bs,Long,Heavy  CP odd (without CP violation)
New physics can contribute in penguin diagrams
Measurements
Lifetimes in flavor specific modes: Bs → Ds, Bs → Dsl
Lifetime in CP even states: Bs  K+ K-, Bs → Ds(*)Ds(*)
May account for most of the width difference
Measure both lifetimes in Bs J/
Separate CP states with angular distributions and measure lifetimes
Look for CP Violation
Many Orthogonal Methods!

10. Bs Lifetime Lifetimes in flavor specific modes: Bs → Ds, Bs → Dsl
Equal mix of Bs,Short,Light and Bs,Long,Heavy at t=0
Measures:
Dominated by Tevatron Measurements

11.  Bs CP Even States
Lifetimes in CP specific, even, modes: Bs  K+ K-,Bs → Ds(*)Ds(*)
CDF: Bs  K+ K-
(Bs→ K+K-)=1.53±0.18 ± 0.02 ps
/ >  0.23  0.03
Shorter than flavor specific
CDF: Bs → DsDs
/ > 2BR(Bs → Ds(*)Ds(*)) > 0.012(95%CL)
DØ: Bs → Ds(*)Ds(*)
Inclusive rate accounts for most of 
/ >   0.036
Contributes to /

12. CP Violation will change this picture
 Bs: Bs J/
Directly measure lifetimes in Bs J/
Separate CP states by angular distribution and measure lifetimes
A0 = S + D wave  P even
A|| = S + D wave  P even
A = P wave  P odd
CP Violation will change this picture
Bs,Short,Light  CP even
Bs,Long,Heavy  CP odd

13.  Bs Results: Bs J/ Assuming no CP violation
CDF:  Bs = 0.02  0.05  0.01 ps-1
DØ:  Bs =   ps-1
Putting all the measurements together
Fall 07, new results ~20% better
Next CP Violation

14. Bshh: Direct CP Violation
Direct CP violation expected to be large in some Bs decays
Some theoretical errors cancel out in B0, Bs CP violation ratios
Challenging because best direct CP violation modes, two body decays, have overlapping contributions from all the neutral B hadrons
Separation: mass, momentum imbalance, and dE/dx
First Observations

15. Bshh: Direct CP Violation
BR(Bs  K) = (5.0  0.75  1.0) x 10-6
Good agreement with recent prediction
ACP expected to be 0.37 in the SM
Ratio expected to be 1 in the SM
New physics possibilities can be probed by the ratio
Lipkin, Phys.Lett. B621 (2005) 126

16. Bs Mixing: Overview -
Measurement of the rate of conversion from matter to antimatter: Bs  Bs
Determine b meson flavor at production, how long it lived, and flavor at decay
to see if it changed!
tag Bs
p(t)=(1 ± D cos mst)

17. Bs Mixing: CDF/DØ Results
March 2005
Nov 2005: Add Ds- 3
and lower momentum Ds-l+
March 2006: Add L00 and SST
April 2006: Use 1fb-1 Data
Add PID and NNs

18. Bs Mixing: CDF Results Key Features Result Sen: 95%CL 31.3ps-1
Sen:
0.2
A/A 6
Prob. Fluctuation
8x10-8
Peak value: ms
17.75ps-1
2.8THz
A >5 Observation!
Can we see the oscillation?

19. Bs Mixing: DØ Results Observed and confirmed at the Tevatron
Key Features
Result
Sen: 95%CL
27.3ps-1
Peak value: ms
18.5ps-1
3 Evidence
Observed and confirmed at the Tevatron
Now calibration data rather than a physics measurement for LHCb
Interesting to look at LHCb physics prospects talks and see what else we can do at the Tevatron!

20. Bs Mixing: CKM Triangle
ms =  0.10 (stat)  0.07 (syst) ps-1
|Vtd| / |Vts| =  (stat + syst)  (lat. QCD)
Tevatron

21. Measurement, statistics limited
BsDsX: CP Violation
CP violation in BsDsX decays
Time dependent,
flavor tagged measurement
Uses known Bs oscillation rate
Now possible due to excellent
oscillation results
Key issue: understanding background
Detector effects, light B, and DsX
DØ has excellent control of detector effects from ability to reverse the magnetic fields
Most Precise assl
Measurement, statistics limited
assl =  

22.  Bs and CPV in Bs J/
Natural next step once Bs oscillations established
Often called the
sin2s analysis
Sensitivity for s in tagged and untagged analysis

23. CPV in Bs J/ Likelihood fit , s plane
CDF: 0.07, 1.8
Likelihood fit , s plane
Uses time independent and time dependent tagged information.
D0: p value 0.085
1.7 from SM
CDF: 0.10, 1.5
Comb: 0.031
2.2
Favoured with all
constraints

24. What Else? Consider B factory sin2 in charmonium vs. s penguin decays
ccs vs css: Polarization and 2s
Equivalent test is Bs J/(css) vs. Bs  (sss)
280 events 3 fb-1

25. Bs Physics Conclusion
Tevatron making large gains in our understanding of Bs Physics
Concentrating on areas where there might be hints of new physics
Precision measurement of ms
On the hunt for direct CP violation
Discrepancy in CP violating phase in Bs J/
Experiments cooperating to produce definitive B physics measurements
One of the primary
goals of the
Tevatron
accomplished!
ms =  0.10 (stat)  0.07 (syst) ps-1
ACP(Bs  K) = 0.39  0.15  0.08
> 2.2
Study of the Bs meson has entered the precision era