B Physics at the Hadron Colliders: Bs Meson and New B Hadrons Introduction to B Physics Tevatron, CDF and DØ b Baryon Selected Bs Results Conclusion Matthew Herndon, March 2007 University of Wisconsin APS April Meeting BEACH 04 J. Piedra 1

If not the Standard Model, 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 Baryogenesis and 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 M. Herndon 2

A Little History d s Everything started with kaons Flavor physics is the study of bound states of quarks. Kaon: Discovered using a cloud chamber in 1947 by Rochester and Butler. Could decay to pions and had a very long lifetime: 10-10 sec Bound state of up or down quarks with a new particle: the strange quark! Needed the weak force to understand it’s interactions. Neutron kaons were some of the most interesting kaons What was that new physics? New particles, Rare decays, CP violation, lifetime/decay width differences, oscillations K0 Rich ground for studying new physics s d M. Herndon 3

B Hadrons s b b u d New physics and the b Hadrons Very interesting place to look for new physics(in our time) Higgs physics couples to mass so b hadrons are interesting Same program. New Hadrons, Rare decays, CP violation, , oscillations State of our knowledge on Heavy b Hadrons last year Hints for Bs seen: by UA1 experiment in 1987. Bs andLb Seen: by the LEP experiments and Tevatron Run 1 Some decays seen However Bs oscillation not directly seen  not measured CP violation not directly seen Most interesting rare decays not seen No excited Bs or heavy b baryons observed b s b u d A fresh area to look for new physics! M. Herndon 4

The Tevatron - 1.96TeV pp collider CDF/DØ Integrated Luminosity Excellent performance and improving each year Record peak luminosity in 2007: 2.8x1032sec-1cm-2 TRIGGERS ARE CRITICAL CDF/DØ Integrated Luminosity ~2fb-1 with good run requirements through end now All critical systems operating including silicon Have doubled the data twice in the last few years B physics benefits from more data M. Herndon 5

CDF and DØ Detectors CDF Tracker Triggered Muon coverage: |η|<1.0 Silicon |η|<2, 90cm long, rL00 =1.3 - 1.6cm 96 layer drift chamber 44 to 132cm Triggered Muon coverage: |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 M. Herndon 6

The Results! New Heavy b Baryons Bs → μμ  Bs and CP violation Combining together excellent detectors and accelerator performance Ready to pursue a full program of B hadron physics Today… New Heavy b Baryons Bs → μμ  Bs and CP violation Direct CP violation Bs Oscillations M. Herndon 7

New B Hadrons = 3/2+(Sb*) Sb: b{qq}, q = u,d; JP = SQ + sqq Lb only established b baryon - LEP/Tevatron Tevatron: large cross section and samples of Lb baryons First possible heavy b baryon: Predictions from HQET, Lattice QCD, potential models, sum rules… = 3/2+(Sb*) Sb: b{qq}, q = u,d; JP = SQ + sqq = 1/2+ (Sb) M. Herndon 8

b Reconstruction Strategy: Establish a large sample of decays with an optimized selection and search for: b+  Lb+ b: Nb = 3184 Estimate backgrounds: Random Hadronization tracks Other B hadrons Combinatoric Extract signal in combined fit of Q distribution M. Herndon 9

b Observation Observe Sb signal for all four expected Sb states > 5s significance level Sb- 59  15  7 Sb+ 32  13  4 Sb-* 69  18  11 Sb+* 77  17  8 Mass differences m(Sb) - m(b) 194.1  1.2  0.1MeV/c2 m(Sb*) - m(Sb) 21.2  1.9  4 MeV/c2 M. Herndon 10

Bs(d) → μ+μ- Method Rare decay that can be enhanced in Higgs, SUSY and other models Relative normalization search Measure the rate of Bs(d) → μ+μ- decays relative to B J/K+ Apply same sample selection criteria Systematic uncertainties will cancel out in the ratios of the normalization Example: muon trigger efficiency same for J/ or Bs s for a given pT 9.8 X 107 B+ events 400pb-1 N(B+)=2225 M. Herndon 11

Discriminating Variables 4 primary discriminating variables Mass Mmm CDF: 2.5σ window: σ = 25MeV/c2 DØ: 2σ window: σ = 90MeV/c2 CDF λ=cτ/cτBs, DØ Lxy/Lxy α : |φB – φvtx| in 3D Isolation: pTB/( trk + pTB) CDF, λ, α and Iso: used in likelihood ratio D0 additionally uses B and  impact parameters and vertex probability Unbiased optimization Based on simulated signal and data sidebands M. Herndon 12

Bs(d) → μ+μ- Search Results CDF Result: 1(2) Bs(d) candidates observed consistent with background expectation Decay Total Expected Background Observed CDF Bs 1.27 ± 0.36 1 CDF Bd 2.45 ± 0.39 2 D0 Bs 0.8 ± 0.2 1.5 ± 0.3 3 BF(Bs  +- ) < 10.0x10-8 at 95% CL BF(Bd  +- ) < 3.0x10-8 at 95% CL D0 Result: First 2fb-1 analysis! BF(Bs  +- ) < 9.3x10-8 at 95% CL Worlds Best Limits! Combined: BF(Bs  +- ) < 5.8x10-8 at 95% CL CDF 1 Bs result: 3.010-6 PRD 57, 3811 1998 M. Herndon 13

New Physics in  Bs  Bs Width-lifetime difference between eigenstates Bs,Short,Light  CP even Bs,Long,Heavy  CP odd New physics can contribute in penguin diagrams Measurements Directly measure lifetimes in Bs J/ Separate CP states by angular distribution and measure lifetimes Measure lifetime in Bs  K+ K- CP even state Search for Bs → Ds(*)Ds(*) CP even state May account for most of the lifetime-width difference Many Orthogonal Methods! M. Herndon 14

 Bs Results: Bs J/ Assuming no CP violation DØ Run II Preliminary DØ Run II Preliminary Assuming no CP violation  Bs = 0.12  0.09  0.02 ps-1 Non 0  Bs D0: PRL 98, 121801 2007 Putting all the measurements together M. Herndon 15

 Bs CP Violation Results Allowing for CP Violation Combine with searches for CP violation in semileptonic B decays  Bs = 0.17  0.09 ps-1  = NP + SM = -0.70 +0.47-0.39 D0: hep-ex/0702030 Consistent with SM  Bs = 0.10  0.03 SM = -0.03 - +0.005 U. Nierste hep-ph/0406300 M. Herndon 16

Bs: 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 Separate with mass, momentum imbalance, and dE/dx First Observations M. Herndon 17

B0: Direct CP Violation Hadron colliders competitive with B factories! -0.107  0.018 +0.007-0.004 Hadron colliders competitive with B factories! M. Herndon 18

Bs: 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 M. Herndon 19

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) M. Herndon 20

Bs Mixing Bs Large samples, good flavor tagging, great time resolution Performance(D2) D0 OST 2.48  0.21  0.07% CDF OST 1.8% CDF SST 3.7%(4.8%) Decay Candidates CDF Bs  Ds(2) 5600 CDF Bs  Ds-*+, Bs  Ds- + 3100 CDF Bs  DslX 61,500 D0 Bs  DslX 41,000(+1600) Large samples, good flavor tagging, great time resolution M. Herndon 21

Bs Mixing: DØ Results Key Features Result Limits: 17-21ps-1 @90CL Sen: 95%CL 16.5ps-1 Sen: A(@17.5ps-1) 0.7 A/A 1.6 Prob. Fluctuation 8% Peak value: ms 19ps-1 Limits: 17-21ps-1 @90CL One experiment with more sensitivity than the whole generation of experiments before! PRL 97, 021802 2006 M. Herndon 22

Bs Mixing: Results Key Features Result 2.8THz A >5 Observation! 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! PRL 97, 242003 2006 Can we see the oscillation? M. Herndon 23

Bs Mixing: CKM Triangle Tevatron ms = 17.77  0.10 (stat)  0.07 (syst) ps-1 |Vtd| / |Vts| = 0.2060  0.0007 (stat + syst) +0.0081(lat. QCD) -0.0060 24

ms = 17.77  0.10 (stat)  0.07 (syst) ps-1 B Physics Conclusion Tevatron making large gains in our understanding of B Physics First new heavy baryon, Sb, observed New stringent limits on rare decays: Precise measurement of  Bs On the hunt for direct CP violation First measurements of ms Factor of 30 improvement over run 1 BF(Bs  +- ) < 9.3-10x10-8 at 95% CL And first look at the CP violating phase  Bs = 0.12  0.09 ± 0.02 ps-1 ACP(Bs  K) = 0.39  0.15  0.08 2.5 -0.18 One of the primary goals of the Tevatron accomplished! ms = 17.77  0.10 (stat)  0.07 (syst) ps-1 M. Herndon 25