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Heavy flavour @ Tevatron Status and prospects

Heavy flavour @ Tevatron Status and prospects. Flavour in the era of the LHC March 2007. Jónatan Piedra MIT. Outline. The Tevatron Collider The D  and CDF II Detectors B s Mixing DG s and  s B  hh’ B  mm L b  J/  L Lifetime Observation of S b Prospects.

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Heavy flavour @ Tevatron Status and prospects

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  1. Heavy flavour @ TevatronStatus and prospects Flavour in the era of the LHC March 2007 Jónatan Piedra MIT

  2. Outline • The Tevatron Collider • The D and CDF II Detectors • Bs Mixing • DGs and s • B  hh’ • B mm • Lb J/L Lifetime • Observation of Sb • Prospects

  3. The Tevatron Collider • ppbar collisions at 1.96 TeV • 2 fb–1 data on tape • Peak luminosity 2.9 x 1032 cm–2s–1 • Average 6 ppbar interactions per bunch crossing • Anticipate luminosity as high as 3 x 1032 cm–2s–1  challenge for detectors, trigger and reconstruction

  4. The D and CDF II Detectors • CDF II • strong central tracking • silicon vertex detector and trigger • particle ID (TOF and dE/dx) • excellent mass resolution • D • excellent coverage of tracking and muon systems • excellent calorimetry and electron ID • 2 T solenoid, polarity reversed weekly • April 2006 Layer 0 installation

  5. Bs Mixing Neutral B Meson Oscillations Lattice QCD, hep/lat-0510113 • The eigenstates of the weak interaction are different from those of the strong interaction  mixing in quark families • Oscillation frequencies Dmd and Dms determine poorly known Vtd and Vts • Theoretical uncertainties reduced in ratio, 11%  3% STRONG (MASS) EIGENSTATES WEAK (FLAVOR) EIGENSTATES

  6. Bs Mixing Signal • Cleanest topology • Includes partially reconstructed decays • Total signal • 8,800 fully reconstructed decays • 61,500 semileptonic decays

  7. Bs Mixing Results Phys. Rev. Lett. 97, 242003 (2006) 1.2 fb-1 Double-sided 90% CL, 17 < Dms < 21 ps-1 Phys. Rev. Lett. 97, 061802 (2006) • Probability that a random fluctuation mimics signal = 8 x 10-8  5.4s

  8. DGs and s Motivation • Light and Heavy Bs mass eigenstates Dms MH – ML DGGL – GH • The mass eigenstates are expected to be almost pure CP eigenstates • The CP violating mixing phase is predicted to be s = (4.2  1.4) x 10-2 A.Lenz & U.Nierste, hep-ph/0612167 • New Physics may alter s leading to a reduction of the observed DGs DGs = DGsSM x |cos s| J. Piedra

  9. DGs and sBs J/ 260 pb-1 CDF update coming soon • 1.1 fb-1 • Bs J/  J/m+m-  K+K- • Fit time dependent angular distributions, mass and lifetime • direct constraint on s • 4-fold ambiguity, s and (p - s) the sign of sins is reversed with the simultaneous reversal of the signs of the cosines of the CP-conserving strong phases d1 and d2 consistent with the SM prediction J. Piedra

  10. DGs and s Flavor Specific Decays • Flavor specific decays of Bs provide independent constraints • An effective mean lifetime tfs = 1/Gfs is related to the physical parameters hep-ph/0201071, p.360 • Use world average value tfs = 1.440  0.036 ps • includes recent D measurement J. Piedra

  11. DGs and s Charge Asymmetry • Another constraint on the parameters of the Bs system • Measurement of the semileptonic charge asymmetry induced by Bs mixing • Measurement “a” • Measurement “b” • “a” and “b”are nearly independent (correlation < 1%) • Combination  best estimate of charge asymmetry in semileptonic Bs input from B-factories

  12. DGs and s Results • Repeat fit to Bs J/ (1 fb-1) with • constraint from charge asymmetry • constraint from WA tfs • The contours indicate error ellipses Dln(L) = 0.5(39% CL) • s ambiguity remains unsolved • For the solution with s < 0, cos d1 > 0 and cos d2 < 0 DGstans = 0.02 ps-1

  13. B  hh’ Motivation • The Tevatron has access to Bs, B0 and baryons • physics program complementary to the e+e-B-factories • Currently accesible BR can constrain theory • compare measurements with allowed regions in spaces of B0  p+p- and Bs  K+K- observables • probe for New Physics J. Piedra

  14. B  hh’ Strategy signal ~ 6,500 expected Lb rare modes three-body B decays combinatorial background • Two sets of optimized cuts • (loose) to measure ACP(B0 K+p-) • (tight) to observe Bs K-p+ and measure N(Bs K-p+) / N(B0 K+p-) • Despite excellent mass resolution (23 MeV/c) modes overlap in a peak • PID resolution is insufficient for event-by-event separation • Fit signal composition with a likelihood that combines information from kinematics (mass and momenta) and particle ID (dE/dx) J. Piedra

  15. B  hh’ BR Results • Measured • Using HFAG 2006 averaged values • BR(B0 → p+p-) in agreement with B-factories measurement

  16. B  hh’ Rare Modes • Signal = 6 modes combination • B0  p+p−/ K+p− and Bs  K+K−already established • Set limits on annihilation modes • Bs  p+p−and B0  K+K− • 3 new rare modes observed

  17. B  hh’ Direct CP Asymmetry • “Is observed direct CP violation in B0  K+p-due to NP? Check SM prediction of equal violation in Bs  K-p+” Lipkin, Phys. Lett. B621:126 (2005) Gronau & Rosner Phys.Rev. D71 074019 (2005) • Expect large ACP(Bs  K-p+) 0.37 • Sign opposite to ACP(B0  K+p-) First measurement of CP asymmetry in the Bs system

  18. B mm Motivation and Strategy • Standard Model prediction very suppressed • Sizeable New Physics enhancement predicted in many scenarios • Blind optimization using signal Monte Carlo and sideband data • Normalize to known B+ J/ K+ • Reconstruct normalization mode in the same data, applying same criteria • Evaluate expected background, open the box and calculate BR or limit

  19. B mm Signal Discrimination MB± 2.5s (~120 MeV) mass window vertex displacement l = LMB / pB angle between pB and decay axis fraction of pT(B) within DR = 1

  20. B mm Results • 780 pb-1 CDF Bs limit • BR(Bs  mm) < 8 (10) x 10-8 @ 90% (95%) C.L. CDF update coming soon (sensitivity x2) • 2 fb-1 DØ Bs limit • BR(Bs mm) < 7.5 (9.3) x 10-8 @ 90% (95%) C.L. • 780 pb-1 CDF B0 limit, world’s best • BR(B0mm) < 2.3 (3.0) x 10-8 @ 90% (95%) C.L. • 110 fb-1 BaBar hep-ex/0408096 • BR(B0mm) < 8.3 x 10-8 @ 90% C.L.

  21. Lb J/L Lifetime Results • CDF and D have measured Lb J/L lifetime • Smaller boost uncertainty than LbLc ln(world average dominated) • Earlier t(Lb)/t(B0) ~ 0.94 predictions were 2s above experiment • new calculations including higher order effects predict lower ratio

  22. Lb J/L Lifetime Summary • Current NLO QCD + 1/mb4 t(Lb)/t(B0) = 0.86 ± 0.05 • HFAG 2005 world average t(Lb)/t(B0) = 0.803 ± 0.047 • New CDF result about 3s above PDG 2006 • New D results consistent with PDG 2006 & CDF • Need more experimental inputs • Soon LbLc+p- lifetime from CDF yield ~ 3,000 J. Piedra

  23. Observation of Sb • Lb (udb) only established b-baryon • Next accessible baryons: uub and ddb states • Look at Lb Lc psample • Signals consistent with lowest lying charged Sb states

  24. Summary • Very fast turn around of results at the Tevatron • D already showing 2 fb-1 results • Competitive and complementary program to B-factories • Bs mixing measured • Dms = 17.77  0.10 (stat.)  0.07 (syst.) ps-1 • First observation of • Bs K-p+ • Lb pK- • Lb pp- • First measurement of direct CPV in Bs • B mm limits ~10-8 • Observation of Sb

  25. Prospects I 360 pb-1 1.3 fb-1, submitted to PRL • Bs mixing phase s not constrained by Dms • DGs and s from • Bs J/ • Bs K+K- • flavor specific decays Bs Dsln, Dsp • semileptonic charge asymmetry ASL • BR(Bs Ds(*) Ds(*) ) ALL THESE MEASUREMENTS SHOULD CONVERGE

  26. Prospects II • Direct measurement of s • measure time dependent CP asymmetry in Bs J/  • ACPmix from Bs J/  (ACPmix, theory = 0.07  0.50) • CKM angle g 51º  20º • D0 mixing (evidence from Belle and BaBar) • D0 direct CP asymmetry • Rare charm decays • D0 l+l’- could be world’s best • D+(s)pmm or Kmm • New b-baryon decay modes • CDF looking at

  27. Backup J. Piedra

  28. Bs Mixing Asymmetry J. Piedra

  29. D0 MixingCharm Mixing • Mixing observed in K0, Bd and Bs, but not yet in D0 • Charm mixing is slower than B or K mixing • Use D*  D0p+ to tag the original flavor as D0 or anti-D0 • D0 K-p +, Cabibbo Favored (CF) • D0 K+p -, Doubly Cabibbo Suppressed (DCS) J. Piedra

  30. D0 MixingBelle and BaBar • Reminder • y = DG / 2G • x = Dm / G • y’ = ycosd – xsind • d = strong phase difference between CF and DCS amplitudes • mixing parameter yCP = t(D0 K-p+) / t(D0 K+K-) • in CP conservation limit yCP = y • Belle hep-ex/0703036 • 540 fb-1 • yCP = 1.31 ± 0.32 (stat) ± 0.25 (syst) % • more than 3s above zero • BaBar hep-ex/0703020 • 384 fb-1 • y’ = 0.97 ± 0.44 (stat) ± 0.31 (syst) % • 3.9s deviation from zero • Evidence for D0 mixing

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