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New Particles and Surprising Results in Heavy Flavor Physics at CDF

This presentation discusses the new particles discovered in heavy flavor physics, including X(3872), Xb, Cascade(b), as well as branching ratios, lifetimes, mixing, and production properties of various B mesons. It also covers rare decays, CP violation, and the challenges faced in triggering and reconstruction of heavy flavor events at the Tevatron.

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New Particles and Surprising Results in Heavy Flavor Physics at CDF

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  1. B Physics Results from CDF Cheng-Ju S. Lin (Fermilab) Lake Louise Winter Institute 20 February 2007

  2. Gold Mine for Heavy Flavor Physics New particles: X(3872), Xb, Cascade(b) … B and D Branching ratios Lifetimes: DG, Lb, Bs, Bc, B+, Bd … Mixing: Bs, Bd, D0 Production properties: s(b), s(J/y), s(D0), … Mass measurements: Bc, Lb, Bs, … CP Violation: Acp(Bhh), Acp(D0Kp), … SURPRISES!? Rare decays: Bsm+m-, BK* m+m-, D0m+m- , …

  3. b b g g b g q b b b b b q g g g q q Flavor Excitation Flavor Creation (gluon fusion) Flavor Creation (annihilation) Gluon Splitting Heavy Flavor Physics in Hadron Environment b’s produced via strong interaction decay via weak interaction • Tevatron is great for heavy flavor: • Enormous b production cross-section, • x1000 times larger than e+e- B factories • All B species are produced (B0, B+,Bs, • Lb, Sb, etc…) • However, • Inelastic (QCD) background is about • x1000 larger than b cross-section • Online triggering and reconstruction is • a challenge: collision rate ~1.7MHz  • tape writing limit ~100Hz

  4. Silicon Vertex Tracker (SVT) CDF is the first hadron collider experiment to be able to trigger on fully hadronic B events • SVT links drift chamber tracks from • Level-1 with silicon hits to compute the • impact parameter of the track. Level-2 SVT Trigger • SVT d0 resolution is ~ 47m • (35m beamline  33m resol). • SVT revolutionized B and • Charm physics at CDF.

  5. Neutral B Meson Oscillations a Im  Vub/Vcb  Vtd l (,) n c b Vcb g b l n u b Vub Re (0,1) (0,0) • In the Standard Model B mixing occurs via the box diagram: • Study of B0 oscillation provides an important test of SM • Ratio of B0and Bs0 oscillation frequencies is related to the side of • the Unitarity triangle (more precise than B0 mixing alone) Study semileptonic B decays BJ/ Ks,D+D-, etc…

  6. Neutral B Meson Oscillations Hadronic Bs decay modes: Golden mode: Partially reconstructed: Multi-body decays: Total hadronic signal: 8700 events • Semileptonic Bs decay modes: • Large sample (~62K events) • However, poorer proper time resolution

  7. Observation of Bs Meson Oscillations P-value=8×10-8 5.4s The SVT trigger is the key to this discovery !!! (2.83 THz) (Combine with B0 mixing) (Dominated by theo. Uncertainties!!!)

  8. Two-body Hadronic B Decays • SVT trigger allows us • to reconstruct Bhh • decays • Rely on TOF and dE/dX • for K, p separation • First observations of: • Looking for two remaining modes: • Bspp • B0KK

  9. CP Asymmetry in B0hh Decays • Our results are very competitive • with the B factories • Acp(BsK+p) is expected to be • large in the S.M. Could measure • it in Run II • Direct CP asymmetries in • Lbhh are in progress • First measurement of CP asymmetry in the Bssystem

  10. Lifetime Measurements LbJ/yL0 Prior lifetime measurements below NLO calculations • Signal: 538 ± 38 Λb events • Result • Use J/y vertex to measure Lb decay length • Major sources of systematics are due to modeling of ct resolution and V0 pointing (World best)

  11. The jury’s still out… Prior world average t(Λb)/t(B0) was lower than the NLO prediction. New CDF result sits about 3s above world average! Need more experimental inputs to conclude the issue. Looking forward to t(Λb) in fully hadronic decay modes, e.g. Λb  Λcp. Larger sample (~3000 signal) Lb Lifetime Summary

  12. Observation of Sb Baryons • Up until now, Lb is the • only observed b-baryon • Look for Sb via Lbp mode • Signals consistent with • lowest lying charged Sb • states with significance • of more than 5s

  13. Summary • Tevatron heavy flavor physics program is in • full swing. What I’ve showed today is only the • “tip of the iceberg” • Discoveries with only 1fb-1: • Bs mixing • Sb baryons • Many new B hadron decay modes • … • With multi-fb-1 of data to come, we are surely to • have more discoveries!!!!

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