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Register a new userMeasurement of the Bs effective lifetime in the J/psi f0(980) final state
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The effective lifetime of the Bs meson in the decay mode Bs->J/psi f0(980) is measured using 1.0/fb of data collected in pp collisions at sqrt(s) = 7 TeV with the LHCb detector. The result is 1.700 +/- 0.040 +/- 0.026 ps where the first uncertainty is statistical and the second systematic. As the final state is CP-odd, and CP violation in this mode is measured to be small, the lifetime measurement can be translated into a measurement of the decay width of the heavy Bs mass eigenstate, Gamma_H = (0.588 +/- 0.014 +/- 0.009)/ps.
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Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -> J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -> J/psi f0, f0 -> pi+ pi-)]/[Gamma(Bs -> J/psi phi, phi -> K+K-)] = 0.252^{+0.046+0.027}_{-0.032-0.033}, where the uncertainties are statistical and systematic, respectively.
We present a study of Bs0 decays to the CP-odd final state J/psi f0(980) with J/psi -> mu+ mu- and f0(980) -> pi+ pi-. Using ppbar collision data with an integrated luminosity of 3.8/fb collected by the CDF II detector at the Tevatron we measure a Bs0 lifetime of tau(Bs0 -> J/psi f0(980)) = 1.70 -0.11+0.12(stat) +-0.03(syst) ps. This is the first measurement of the Bs0 lifetime in a decay to a CP eigenstate and corresponds in the standard model to the lifetime of the heavy Bs0 eigenstate. We also measure the product of branching fractions of Bs0 -> J/psi f0(980) and f0(980) -> pi+ pi- relative to the product of branching fractions of Bs0 -> J/psi phi and phi -> K+ K- to be R_f0/phi = 0.257 +_0.020(stat) +-0.014(syst), which is the most precise determination of this quantity to date.
This paper reports the first measurement of the effective B_s^0 -> J/{psi} K_S^0 lifetime and an updated measurement of its time-integrated branching fraction. Both measurements are performed with a data sample, corresponding to an integrated luminosity of 1.0 fb^{-1} of pp collisions, recorded by the LHCb experiment in 2011 at a centre-of-mass energy of 7 TeV. The results are: tau_J/{psi}K_S^0 = 1.75 +/- 0.12 (stat) +/- 0.07 (syst) and BR(B_s^0 -> J/{psi} K_S^0) = (1.97 +/- 0.23) X 10^{-5}. For the latter measurement, the uncertainty includes both statistical and systematic sources.
The decay Bs -> J/psi K+ K- is investigated using 0.16/fb of data collected with the LHCb detector using 7 TeV pp collisions. Although the J/psi phi channel is well known, final states at higher K+K- masses have not previously been studied. In the K+K- mass spectrum we observe a significant signal in the f2(1525) region as well as a non-resonant component. After subtracting the non-resonant component, we find B(Bs->J/psi f_2(1525))/B(Bs->J/psi phi)=(26.4 +/- 2.7 +/- 2.4)%.
We briefly discuss measurements of CP violation in Bs --> J/psi phi decay. Both the phenomenology of Bs mixing and the importance of the measurement to searches for new physics, as well as technical details and issues with the analysis are included. While current results are consistent with the standard model, even large contributions from new physics cannot be excluded.
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