1 / 25

B Physics at the Hadron Colliders: B s Meson and New B Hadrons

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

farrah
Download Presentation

B Physics at the Hadron Colliders: B s Meson and New B Hadrons

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. If not the Standard Model, What? Standard Model fails to answer many fundamental questions Look for new physics that could explain these mysteries Look at weak processes which have often been the most unusual • 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? • Standard Model predictions validated to high precision, however M. Herndon 2

  3. A Little History d s Rich ground for studying new physics K0 • 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 M. Herndon 3

  4. B Hadrons s b b u d A fresh area to look for new physics! • 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. • BsandLbSeen: 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 M. Herndon 4

  5. The Tevatron TRIGGERS ARE CRITICAL B physics benefits from more data - • 1.96TeV pp collider • Excellent performance and improving each year • Record peak luminosity in 2007: 2.8x1032sec-1cm-2 • 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 M. Herndon 5

  6. CDF and DØ Detectors EXCELLENT TRACKING: EFFICIENCY EXCELLENT TRACKING: MASS RESOLUTION EXCELLENT TRACKING: TIME RESOLUTION • CDF Tracker • Silicon |η|<2, 90cm long, rL00 =1.3 - 1.6cm • 96 layer drift chamber 44 to 132cm • Triggered Muon coverage: |η|<1.0 • DØ Tracker • Silicon and Scintillating Fiber • Tracking to |η|<2 • New L0 on beam pipe! • Triggered Muon coverage: |η|<2.0 M. Herndon 6

  7. The Results! • 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

  8. New B Hadrons • 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

  9. bReconstruction • 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

  10. bObservation • Observe Sb signal for all four expected Sb states • > 5s significance level • Mass differences M. Herndon 10

  11. Bs(d)→ μ+μ-Method 9.8 X 107B+ events • 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 400pb-1 N(B+)=2225 M. Herndon 11

  12. Discriminating Variables 4 primary discriminating variables • Mass Mmm • CDF: 2.5σwindow:σ = 25MeV/c2 • DØ: 2σwindow: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

  13. Bs(d)→ μ+μ-SearchResults Worlds Best Limits! BF(Bs +- ) < 10.0x10-8 at 95% CL BF(Bd +- ) < 3.0x10-8 at 95% CL BF(Bs +- ) < 9.3x10-8 at 95% CL BF(Bs +- ) < 5.8x10-8 at 95% CL CDF Result: 1(2) Bs(d)candidates observedconsistent with background expectation D0 Result: First 2fb-1 analysis! Combined: CDF 1 Bs result: 3.010-6 PRD 57, 3811 1998 M. Herndon 13

  14. New Physics in Bs Many Orthogonal Methods! • 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 M. Herndon 14

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

  16. Bs CP Violation Results Bs = 0.17  0.09 ps-1  = NP + SM = -0.70 +0.47-0.39 • Allowing for CP Violation • Combine with searches for CP violation in semileptonic B decays 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

  17. Bs: Direct CP Violation First Observations • 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 M. Herndon 17

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

  19. 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

  20. 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

  21. Bs Mixing tag Bs • Large samples, good flavor tagging, great time resolution M. Herndon 21

  22. Bs Mixing: DØ Results One experiment with more sensitivity than the whole generation of experiments before! Limits: 17-21ps-1 @90CL PRL 97, 021802 2006 M. Herndon 22

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

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

  25. B Physics Conclusion BF(Bs +- ) < 9.3-10x10-8 at 95% CL Bs = 0.12  0.09 ± 0.02 ps-1 ACP(Bs  K) = 0.39  0.15  0.08 • 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 And first look at the CP violating phase 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

More Related