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Rare Bottom and Charm Decays at the Tevatron

Rare Bottom and Charm Decays at the Tevatron. Dmitri Tsybychev (SUNY at Stony Brook) On behalf of CDF and D0 Collaborations Flavor Physics and CP-Violation Taiwan, May 8, 2008. Rare Decays. Electroweak symmetry breaking determines flavor structure CKM matrix, FCNC, CP-violation

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Rare Bottom and Charm Decays at the Tevatron

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  1. Rare Bottom and Charm Decays at the Tevatron Dmitri Tsybychev (SUNY at Stony Brook) On behalf of CDF and D0 Collaborations Flavor Physics and CP-Violation Taiwan, May 8, 2008

  2. Rare Decays • Electroweak symmetry breaking determines flavor structure • CKM matrix, FCNC, CP-violation • Rare decays are instrumental probes • CKM matrix • Sizeable deviations – sign of New Physics • FCNC decays are forbidden at tree level in the SM • Rates are highly suppressed in SM • NP allows tree level processes, enhancement in loops • Look for • B0(s )→ μ+μ- • B±0(s)→ h μ+μ- • D0 → μ+μ- • D±→ π±μ+μ- D. Tsybychev

  3. b g b g g Gluon Splitting q b Flavor Creation b g q b b q q Flavor Excitation B Physics at the Tevatron - Mechanisms for b production in pp collisions at 1.96 TeV • Total inelastic cross section at the Tevatron is ~1000 larger than b cross section • Plethora of states accessible only at the Tevatron: Bs, Bc, Λb, Ξb, Σb… • Large backgrounds suppressed by triggers that target specific decays s(bb)

  4. Analysis Procedures • Preselection of dimuon events • Trigger • Selection optimization • Blind analysis • Avoid biases • Side-band background subtraction • Normalization to resonant decays in similar final state • Large, well-known BR in SM • Efficiency normalization • Significant signal – perform measurement • Otherwise set limit for relevant process D. Tsybychev

  5. Isolation Flight length significance p impact parameter significance Discriminating Variables D. Tsybychev

  6. B0(s)→μ+μ- • Br(B0s→μ+μ-) = (3.42 ± 0.54)x10-9 Buras, PLB 566, 115 (2003) • Br(B0d→μ+μ-) = (1.00 ± 0.14)x10-9 suppressed by (Vtd/Vts)2 • New Physics contribution: • MSSM ~tan6(b), for largetan(b) • SUSY with R-parity violation (RPV) • Z’ with off diagonal couplings D. Tsybychev

  7. B0(s)→μ+μ- Selection and Optimization • Signal: MC • Background: data mass sidebands • Final selection • Likelihood ratio (D0) • Neural network (CDF) • Check selection with control samples • Misidentified muon • Same sign muons D. Tsybychev

  8. B0(s)→μ+μ- Normalization • Combinatorial backgrounds estimated from fit in mass sidebands and propagated to signal region • BR normalized to B±→J/ψK± D. Tsybychev

  9. B0(s)→μ+μ- Results • No excess over expected background observed B0s→μ+μ- B0d→μ+μ- CDF < 4.7x10-8 < 1.5x10-8 PRL 100,101802 (2008) D0 < 7.3x10-8 D0 Note 5344 • New HFAG average < 4.7 x10-8 @ 90% CL Most stringent to date! D. Tsybychev

  10. B0s→μ+μ- Prospects D. Tsybychev

  11. B(±,0)(s)→h(±,0)μ+μ- • Non resonant decays via box or penguin diagrams • BaBar/Belle: • B±u→Km+m- PRD73, 092001 (2006) • B0d→K*m+m- PRL96, 251801 (2006) • Look for B0s→fm+m- • Prediction: BR(B0s→fm+m-) =1.6x10-6 JPHYS G 29, 1103 (2003) • NP • Larger BR • Modified invariant mm mass • Modified angular distributions Fourth Generation PRD 77, 014016 (2008) D. Tsybychev

  12. B(±,0)(s)→h(±,0)μ+μ- Observations • Remove resonant J/ψ,ψ(2S) by cutting on invariant mm mass 7.5±1.5 2.4 44.7±5.8 4.5 18.5±3.6 2.9 D. Tsybychev

  13. B(±,0)(s)→h(±,0)μ+μ- Results BR(B0s→fm+m-) @ 90%CL CDF(hep-ex/0804.3908) < 5.0x10-6(includes uncertainty on normalization channel) D0 (PRD 74 , 031107 (2006)) < 3.2x10-6 B(±,0)(s)→h(±,0)l+l- D. Tsybychev

  14. D0→μ+μ- • B0s→μ+μ- vs D0→μ+μ- • down quark sector vs up quark sector • Short range contribution BR~10-18 • GIM suppressed • Long range contribution BR ~ 4 x 10-13 Burdman et al. hep-ph/0112235 • Significant enhancement possible in SUSY with R-parity violation Long range SM SUSY with R-parity violation D. Tsybychev

  15. D0→μ+μ- Analysis • Events from two-track trigger • Normalize to D0→pp to cancel acceptance and trigger effects • Background reduction by D* tag • Muon ID efficiency from J/ψ→μμ data • Muon mistag rate from D0→Kp • Background estimated from MC • Dominant background from B → μμX • Reduced by the impact parameter and lifetime significance cuts D. Tsybychev

  16. Results BR(D0 → μ+μ-) < 4.3 x 10-7 at 90% CL CDF Note 9226 λ21kλ22k = 1.5√ BR(D0 → μ+μ-) < 9.8 × 10-4 D. Tsybychev

  17. D+(s)→π±μ+μ- • Orthogonal to B0s→μ+μ- • Effects in up-quark sector • factors of >1000 over SM not ruled out • Long distance resonance production • BR = 1.9x10-6 • Short distance continuum production Little Higgs models with new up sector vector quark Fajfer et al. hep-ph/0511048 RPV in the up sector and not the down sector Burdman et al. hep-ph/0112235 D. Tsybychev

  18. Resonant D+(s) Decays • Resonant production • Selection of events with m(μμ) in φ region • N(Ds+) = 254 ± 36 • N(D+) = 115 ± 31 • Statistical significance 8 for Ds+ and D+, 4.1 for D+ • First observation for Ds • First evidence for D+ • BR(D+→φπ+→μ+μ-π+) = (1.8 ± 0.5 ± 0.6) x 10-6 D. Tsybychev

  19. Continuum D+(s) Decays • Exclude resonant φ→μμ mass region • 19 candidates in D+ window • Background expectation 25.8 ± 4.6 (p-value=0.14) • Normalize to D+→φπ+ • BR(D+→ μμπ+) < 3.9 x 10-6 @ 90% CL PRL 100, 101801(2008) D. Tsybychev

  20. Summary • B, D hadron decays provide a Sensitive Probe of EW Symmetry Breaking & Physics Beyond the SM • Allow classes of models to be favored/ruled out • Complementary to direct searches for new particles • The CDF and DØ experiments are making major contributions to CKM measurements • World’s best limits in B,D rare decays • Complimentary to B factories • Adding more data every day • Significant reduction of New Physics parameter space • Bounds on general flavor mixing • Paving the way for LHC D. Tsybychev

  21. BACKUP SLIDES

  22. The Tevatron Accelerator • World’s highest energy collider • Proton-antiproton synchrotron • Experiments CDF and DØ • Run II (2001-2010?) • s = 1.96 TeV • Current peak luminosity L~3 x 1032 cm-2s-1 • Expect up to L= ∫Ldt = 8 fb-1 integrated luminosity in Run II • Large pp cross-section • High collision rate 1.7 MHz D. Tsybychev

  23. Data Collected D. Tsybychev

  24. D0→μ+μ- Summary D. Tsybychev

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