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Register a new userMeasurement of the $B_s^0$ meson lifetime in $D_s^+pi^-$ decays
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We present a measurement of the ratio of the Bs meson lifetime, in the flavor-specific decay to $D_s^+pi^-$, to that of the B0 meson. The pp collision data used correspond to an integrated luminosity of 1/fb, collected with the LHCb detector, at a center-of-mass energy of 7 TeV. Combining our measured value of 1.010 +/- 0.010 +/- 0.008 for this ratio with the known lifetime, we determine the flavor-specific Bs lifetime to be tau(Bs) = 1.535 +/- 0.015 +/- 0.014 ps, where the uncertainties are statistical and systematic, respectively. This is the most precise measurement to date, and is consistent with previous measurements and theoretical predictions.
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We have studied Bs0 -> Ds- pi+ and Bs0 -> Ds^(-/+) K^(+/-) decays using 23.6 /fb of data collected at the Upsilon(5S) resonance with the Belle detector at the KEKB e+e- collider. This highly pure Bs0 -> Ds- pi+ sample is used to measure the branching fraction, BR(Bs0 -> Ds- pi+)=[3.67 +0.35,-0.33}(stat.) +0.43,-0.42(syst.) +-0.49(f_s)] x 10^{-3} (f_s=N(Bs(*) Bs(*)bar)/N(bbar b)) and the fractions of Bs0 event types at the Upsilon(5S) energy, {in particular N(Bs* Bs*bar}/N(N(Bs(*) Bs(*)bar)=(90.1 +3.8,-4.0 +-0.2)%. We also determine the masses M(Bs0)=(5364.4 +-1.3 +-0.7) MeV/c^2 and M(Bs*)=(5416.4 +-0.4 +-0.5) MeV/c^2. In addition, we observe Bs0 -> Ds^(-/+) K^(+/-) decays with a significance of 3.5sigma and measure BR(Bs0 -> Ds^(-/+) K^(+/-))=[2.4 +1.2,-1.0(stat.) +-0.3(syst.) +-0.3(f_s)] x 10^{-4}.
We report the measurements of the $CP$-violating parameters in $B_s^0 to D_s^{mp} K^{pm}$ decays observed in $pp$ collisions, using a data set corresponding to an integrated luminosity of $3.0,text{fb}^{-1}$ recorded with the LHCb detector. We measure $C_f = 0.73 pm 0.14 pm 0.05$, $A^{Delta Gamma}_f = 0.39 pm 0.28 pm 0.15$, $A^{Delta Gamma}_{overline{f}} = 0.31 pm 0.28 pm 0.15$, $S_f = -0.52 pm 0.20 pm 0.07$, $S_{overline{f}} = -0.49 pm 0.20 pm 0.07$, where the uncertainties are statistical and systematic, respectively. These parameters are used together with the world-average value of the $B_s^0$ mixing phase, $-2beta_s$, to obtain a measurement of the CKM angle $gamma$ from $B_s^0 to D_s^{mp} K^{pm}$ decays, yielding $gamma = (128,_{-22}^{+17})^circ$ modulo $180^circ$, where the uncertainty contains both statistical and systematic contributions. This corresponds to $3.8,sigma$ evidence for $CP$ violation in the interference between decay and decay after mixing.
The element $|V_{cb}|$ of the Cabibbo-Kobayashi-Maskawa matrix is measured using semileptonic $B_s^0$ decays produced in proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. Rates of $B_s^0 to D_s^{-} mu^+ u_{mu}$ and $B_s^0 to D_s^{*-} mu^+ u_{mu}$ decays are analyzed using hadronic form-factor parametrizations derived either by Caprini, Lellouch and Neubert (CLN) or by Boyd, Grinstein and Lebed (BGL). The measured values of $|V_{cb}|$ are ${(41.4 pm 0.6 pm 0.9 pm 1.2)times 10^{-3}}$ and ${(42.3 pm 0.8 pm 0.9 pm 1.2)times 10^{-3}}$ in the CLN and BGL parametrization, respectively. The first uncertainty is statistical, the second systematic, and the third is due to the external inputs used in the measurement. These results are in agreement with those obtained from decays of $B^+$ and $B^0$ mesons. They are the first determinations of $|V_{cb}|$ at a hadron-collider experiment and the first using $B_s^0$ meson decays.
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.
We report measurements of the branching fractions and $CP$ asymmetries for $D_s^{+} rightarrow K^{+} eta $, $D_s^{+} rightarrow K^{+} pi^0 $, and $D_s^{+} rightarrow pi^{+} eta $ decays, and the branching fraction for $D_s^{+} rightarrow pi^{+} pi^0$. Our results are based on a data sample corresponding to an integrated luminosity of 921 fb$^{-1}$ collected by the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. Our measurements of $CP$ asymmetries in these decays are the most precise to-date; no evidence for $CP$ violation is found.
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