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

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

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!

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!

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

CDF and DØ Detectors CDF Tracker Triggered Muons and SVT: |η|<1.0 Silicon |η|<2, 90cm long, rL00 =1.3 - 1.6cm 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

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

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) 5821.4  0.2  0.6 MeV/c2 m(Bs1) Other Tevatron discoveries: Bc(CDF,DØ), b(CDF), b(CDF,DØ), b(DØ)

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!

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

 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 / > -0.08  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  / > 0.088  0.033  0.036 Contributes to /

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

 Bs Results: Bs J/ Assuming no CP violation CDF:  Bs = 0.02  0.05  0.01 ps-1 DØ:  Bs = 0.085  0.075  0.006 ps-1 Putting all the measurements together Fall 07, new results ~20% better Next CP Violation

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

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

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)

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

Bs Mixing: CDF Results Key Features Result Sen: 95%CL 31.3ps-1 Sen: A(@17.5ps-1) 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?

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!

Bs Mixing: CKM Triangle ms = 17.77  0.10 (stat)  0.07 (syst) ps-1 |Vtd| / |Vts| = 0.2060  0.0007 (stat + syst)  0.0075 (lat. QCD) Tevatron

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 = -0.0024  0.0117  0.0020

 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

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

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

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 = 17.77  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