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B s Lifetime Difference Measurements from Tevatron

B s Lifetime Difference Measurements from Tevatron. B s lifetime difference from various channels B s  J/ +  B s  K + K - B s . Kin Yip. BEACH 2006, Lancaster, July 2-8, 2006. Neutral Meson Mixing. *. *. Quark mixing  non-diagonal Hamiltonian for

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B s Lifetime Difference Measurements from Tevatron

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  1. Bs Lifetime Difference Measurements from Tevatron • Bs lifetime difference from various channels • Bs J/ +  • BsK+ K- • Bs Kin Yip BEACH 2006, Lancaster, July 2-8, 2006 Kin Yip

  2. Neutral Meson Mixing * * • Quark mixing  non-diagonal Hamiltonian for • Diagonalizing the Hamiltonian results in • two mass eigenstates and • two masses mH and mL, with Dm  mH – mL • two decay widths GH and GL, with DG  GL GH (> 0 in Standard Model) dominated by top quark contribution

  3. Bs System and CP violation c CP violating weak phase 2bs df (SM) • In Standard Model,   2λ2η(0.03), very small. • Much larger measurement of   a striking signal of new physics in Bs – Bs mixing. Bs J/ +  BsK+K- & • New physics tends to increase  smaller • Any dependence on ms cancels in untagged samples. Kin Yip

  4. Untagged Bs J/ +  Decay • Bs J/y f : • Pseudoscalar  Vector Vector decay • Three waves: S, P, D, orA0, A||, A┴ • Both CP-even and CP-odd present, but separated in angular distributions • measure two lifetimes • S, D (Parity, CP even) : • linear combination ofA0, A|| • P (Parity, CP odd) :A┴ • R┴  |A┴(t=0)|2  Kin Yip

  5. Untagged Bs Decay Rate in Time & Angles correction for acceptances, kinematic cuts • d1Arg[A||(0)*A┴(0)]and d2Arg[A0(0)*A┴(0)] are CP-conserving strong phases • No dependence on ms Kin Yip

  6. Maximum Likelihood Fit Simultaneous fit to mass, proper decay length and 3 angles using an unbinned maximum log-likelihood method 30 parameters: 1 fsig = signal fraction 2 signal mass, width 3 A , |A0|2-|A|||2, 1 strong phase 1 c = c / ,  = (L+ H) /2 1  =  L-H 3 bkg mass (1 prompt, 2 long-lived) 1 (ct ) scale 6 bkg ct shape 4 bkg transversity (2 prmpt + 2 long-lived) 4 bkg angle φ (2 prompt + 2 long-lived) 2 bkg angle ψ (1 prompt + 1 long-lived) 2 bkg “interference” (1 prompt + 1 bkg) set df = 0 • CDF should have similar no. of parameters Kin Yip

  7. All events Bs  J/ +  and  Preliminary ~0.8 fb1 3 angle q, f, y analysis : Nsignals = 978  45 D0 (PRL 2005) used 1 angle, θ, 513 events Kin Yip

  8. Data:Fit projections in signal regions   q (transversity) Kin Yip

  9. Earlier, PRL 94, 101803, 2005, CDF has used a similar 3 angle ( q, f, y ) fit/analysis with 260 pb-1 ofdata • ~260 pb-1 data Kin Yip

  10. NNewew results based on X2 • Withd1 freeandd2 = 0, we obtain= -0.9 ± 0.7; • CP-violating angle df ~consistent with 0 (no CP violation) within statistical uncertainty of ± 0.7. • Working on to constrain all these d1/d2and better. Kin Yip

  11. Combined: DG = 0.18  0.09 ps1  = 1/G =1.520  0.068 ps R. Van Kooten:hep-ex/0606005 Kin Yip

  12. decay trigger bias detector smearing BsK+K- lifetime analysis CP-even  lifetime of the CP-even state Add lifetime information to the fit of composition (of various hadronic states): • Trigger bias for signal is extracted from detailed simulation. • Procedure validated in unbiased B → J/ψX decays from dimuon trigger. • Check that lifetime fits of samples with/without applying track-trigger cuts yield consistent results. • Lifetime p.d.f for background is extracted from higher mass data sideband. Kin Yip

  13. BsK+K- lifetime results (360 pb-1) BsK+K- is CP-even (~ 5% uncertainty): has the lifetime of “light Bs” : Combine with HFAG average (τL2+ τH2)/(τL + τH ): Dominant systematics : • detector alignment; • input pT(B) in simulation; • lifetime model of background; • dE/dx model; • trigger-bias.

  14. Precise measurement of flavor-specific decays further constrain s and s. See E. de la Cruz-Burello’s talk ! R. Van Kooten:hep-ex/0606005 Kin Yip

  15. and S CP Kin Yip

  16. : : , Kin Yip

  17. Bs DS+ DS- (exclusive hadronic mode) • 1st observation of this fully reconstructed decay • Working on to extract S • good prospect with 1 fb-1 Kin Yip

  18. 2.3  from zero, new physics tends to reduce the measureds R. Van Kooten:hep-ex/0606005 Kin Yip

  19. comparison between expt. and theory • Updating from Phys. Lett. B 459, 631 (1999) by U. Nierste:  SM prediction: • Expt. meas. from sand latest ms: Disappointingly in agreement with Standard Model prediction ! Kin Yip

  20. Summary • CP eigenstate mixures and branching fraction measurements now give a “world average” of s ~2.3  away from zero; • Results are consistent with SM so far; • More results from Tevatron (and elsewhere) will pin s down to greater accuracy. Kin Yip

  21. BACKUP Kin Yip

  22. Lifetime Difference & CP violation • Bs J/ :Pseudoscalar  Vector – Vector • Decay amplitude decomposed into 3 linear polarization states • A0 = S + D wave  P even • A|| = S + D wave  P even • A = P wave  P odd • If CP violation neglected  interpreted as lifetimes of 2 mass eigenstates: • Bs,Light  CP even • Bs,Heavy  CP odd • angular distributions are different • Angular analysis separates CP eigenstates  measure two lifetimes Kin Yip

  23. (r, h) a g b (0,0) (1,0) CKM Matrix and Unitarity triangle Relates quark mass and weak eigenstates SM: CP-violating processes solely related to one phase in CKM. ’bs’ (A ‘squashed’ unitary triangle) ‘bd’ (THE unitary triangle) Large effort in B physics Mainly at B factories • bbs, small in SM Interesting to check how small/big bs really is. Currently: Tevatron domain Kin Yip

  24. Background mass region Fit projection (lifetime) All events • Signal mass region  Kin Yip

  25. H(cos y) flat distribution Detector Acceptance (MC & data) F() = 1 + J cos(2) + K cos2(2) G(cos ) = 1 + Bcos2 + Ccos4 Kin Yip

  26. 1 - 2 Systematics • One “outlyer”  treat its effect as systematic uncertainty • Event Run #: 210344 Event #:23385781 • unlikely signal or background • Signal: mass 2.3  from peak, lifetime 8.5 x mean • Bkg: 10.2 x mean for “right slope long” Kin Yip

  27. Some selection cuts data before last Tevatron shutdown Total number of BsJ/y fcandidates: 21380 (PRL 2005: 9699) Kin Yip

  28. Data Kin Yip

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