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B s Mixing and Lifetime Difference at CDF

Sinéad M. Farrington for the CDF collaboration ICHEP July 2008 Philadelphia. B s Mixing and Lifetime Difference at CDF. B s Physics at CDF B s mixing B s lifetime difference See related talks at this conference: CP Violation in B s decays at CDF , Diego Tonelli (Thursday)

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B s Mixing and Lifetime Difference at CDF

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  1. Sinéad M. Farrington for the CDF collaboration ICHEP July 2008 Philadelphia Bs Mixing and Lifetime Difference at CDF

  2. Bs Physics at CDF • Bs mixing • Bs lifetime difference • See related talks at this conference: • CP Violation in Bs decays at CDF, Diego Tonelli (Thursday) • Measurements of B hadron lifetimes, Satyajit Behari (Friday) • Heavy Flavour theory, Tobias Hurth (Monday) This talk - 2

  3. Ecom=2TeV - p CDF p Ep=0.98TeV Ep=0.98TeV 1km D0 ECoM=2TeV The Tevatron - Fermilab, Chicago Currently the world’s highest energy collider • Hadron collisions produce a wide spectrum of b hadrons • Bs has not been copiously produced at the B factories • Tevatron (LHC) are ideal places in which to study this system 3

  4. MATTER ANTIMATTER b b u, c, t, ? s b s s s b Bs Bs Bs 0 0 0 Bs 0 u,c,t,? 0 Bs Physics Bound states: Matterantimatter: NEW PHYSICS? Vts* occurs via W+ W- Vts 0 0 • The mass eigenstates (H and L) are superpositions of Bs and Bs • System characterised by 5 parameters: • masses: mH, mL lifetimes: GH, GL(G=1/t), phase:bs • Dms measured very precisely

  5. 1 fb-1 Dms Measurement Phys. Rev. Lett. 97, 242003 (2006) (5.4s significance) ms = 17.77±0.10(stat)±0.07(syst) ps-1 Extracted parameters dominated by theoretical errors |Vts / Vtd|= 0.2060 ± 0.0007 (exp)+0.0081(theo) -0.0060 CDF now focuses on DG=GH-GL, bs (Tonelli), G= (GH+GL)/2 (Behari)

  6. 0 Bs Physics • DG so far measured imprecisely • Extra test of Standard Model – new physics can still enter through the phase • Want to test the relation ΔΓ= ΔΓSMx |cos 2bs| JHEP06 (2007) 072

  7. Assume no CP violation: BsL = CP even, BsH = CP odd • 1) Measure DG and Gs directly – resolve the CP eigenstates by angular • analysis (e.g. Bs→ J/yf) • 2) CP specific – proportion of CP even/odd is known • Fit a single exponential (e.g. Bs→ K+K- ) Measuring DG - 7

  8. 2.8 fb-1 Direct measurement: Bs→J/yf • Perform simultaneous mass, lifetime, angular fit • Pseudo scalar→2 vectors: S,D wave (CP even) • and P wave (CP odd) • Angular distributions give information on CP • composition J/y rest frame f rest frame

  9. Bs→J/yf Results • Simultaneous fit to mass, lifetime, angular parameters • Assume no CP violation cs = 459 ± 12 (stat) ± 3 (sys)m  = 0.02 ± 0.05 (stat) ± 0.01 (sys) ps-1 |A0| = 0.508 ± 0.024 (stat) ± 0.008 (sys) |A//| = 0.241 ± 0.019 (stat) ± 0.007 (sys) Published 1.7fb-1 analysis: Phys. Rev. Lett. 100, 121803 (2008) Predicted DG 0.096± 0.039ps-1 (arxiv: 0802.0977)

  10. Bs→J/yf Results • Analysis with flavour tagging shown earlier this session (Tonelli) • Allowing for CP violation and tagging induces bias • Cannot obtain DG and bs independently • Quote a confidence region • Problem inherent to the • fitter with low statistics

  11. 0.36 fb-1 • Assume no CP violation: BsL = CP even, BsH = CP odd • b ccs decay (e.g. Bs Ds Ds) is pure CP even • Thus a lifetime measurement of Bs Ds Ds would measure GL • Branching ratio is related to DG/G • (neglect small CP odd component) CP specific: Bs Ds Ds 11

  12. CP specific: Bs Ds Ds • BR (Bs Ds Ds) measured relative to B0Ds D- • Three Ds decay modes reconstructed in each case Phys. Rev. Lett. 100, 021803 (2008) Bs Ds Ds: Control mode yield: 395 Signal mode yield: 23 95% C.L.: 12 Compare with prediction: DG/G=0.147± 0.060

  13. 0.36 fb-1 CP specific: Bs→ KK • Lifetime measurement interesting since ~100% CP even • B→hh decays can be resolved at CDF • Displaced track trigger • Good mass resolution

  14. CP specific: Bs→ KK Lifetime fit: τ(Bs→ K+K-)=1.53±0.18(stat) ± 0.02(sys) ps Use HFAG flavour specific t=1.454±0.040 ps (Working on update with t stat error 0.06-0.09ps in >2fb-1)

  15. Accurate measurement of Dms • Several ways of measuring DG have been deployed • In the presence of new physics, these may not agree with one another • Increased precision in Tevatron analyses may reveal hints of new physics Conclusions - ms = 17.77±0.10(stat)±0.07(syst) ps-1 Vts / Vtd= 0.2060 ± 0.0007 (exp)+0.0081(theo) -0.0060 (95% C.L.) 15

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