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Register a new userPrecision measurement of $CP$ violation in $B_s^0 to J/psi K^+K^-$ decays
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The time-dependent $CP$ asymmetry in $B_s^0 to J/psi K^+K^-$ decays is measured using $pp$ collision data, corresponding to an integrated luminosity of $3.0$fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of $7$ and $8$TeV. In a sample of 96 000 $B_s^0 to J/psi K^+K^-$ decays, the $CP$-violating phase $phi_s$ is measured, as well as the decay widths $Gamma_{L}$ and $Gamma_{H}$ of the light and heavy mass eigenstates of the $B_s^0-bar{B}_s^0$ system. The values obtained are $phi_s = -0.058 pm 0.049 pm 0.006$ rad, $Gamma_s equiv (Gamma_{L}+Gamma_{H})/2 = 0.6603 pm 0.0027 pm 0.0015$ps$^{-1}$, and$DeltaGamma_s equiv Gamma_{L} - Gamma_{H} = 0.0805 pm 0.0091 pm 0.0032$ps$^{-1}$, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of those quantities to date. A combined analysis with $B_s^{0} to J/psi pi^+pi^-$ decays gives $phi_s = -0.010 pm 0.039 $rad. All measurements are in agreement with the Standard Model predictions. For the first time the phase $phi_s$ is measured independently for each polarisation state of the $K^+K^- $ system and shows no evidence for polarisation dependence.
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Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $overline{B}{}^0$ mesons to the $J/psi K^0_S$ final state. The data sample corresponds to an integrated luminosity of $3.0,text{fb}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8,text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $overline{B}{}^0$ decays yields $S = 0.731 pm 0.035 , text{(stat)} pm 0.020 ,text{(syst)}$ and $C = -0.038 pm 0.032 , text{(stat)} pm 0.005,text{(syst)}$. In the Standard Model, $S$ equals $sin(2beta)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.
The time-dependent CP asymmetry in B_s^0to J/psi K^+K^- decays is measured using $pp$ collision data at sqrt{s}=7TeV, corresponding to an integrated luminosity of 1.0fb^-1, collected with the LHCb detector. The decay time distribution is characterised by the decay widths Gamma_L and Gamma_H of the light and heavy mass eigenstates of the B_s^0--bar{B}_s^0 system and by a CP-violating phase phi_s. In a sample of 27,617 B_s^0to J/psi K^+K^- decays, where the dominant contribution comes from B_s^0to J/psiphi decays, these parameters are measured to be phi_s = 0.07 pm 0.09 (stat) pm 0.01 (syst) rad, Gamma_s equiv (Gamma_L+Gamma_H)/2 = 0.663 pm 0.005 (stat) pm 0.006 (syst) ps^-1, DeltaGamma_s equiv Gamma_L -Gamma_H = 0.100 pm 0.016 (stat) pm 0.003 (syst) & ps^-1, corresponding to the single most precise determination of phi_s, DeltaGamma_s and Gamma_s. The result of performing a combined analysis with B_s^{0} to J/psi pi^+pi^- decays gives phi_s = 0.01 pm 0.07 (stat) pm 0.01 (syst) rad, Gamma_s = 0.661 pm 0.004 (stat) pm 0.006 (syst) ps^-1, DeltaGamma_s = 0.106 pm 0.011 (stat) pm 0.007 (syst) & ps^-1. All measurements are in agreement with the Standard Model predictions.
The first measurement of ${C!P}$ asymmetries in the decay ${B_s^0to J/psi overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0,fb^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8,mathrm{TeV}$. Together with constraints from ${B^0to J/psi rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${C!P}$-violating phase ${{phi}_{s}}$, measured through ${B_s^0}$ decays to charmonium.
The decays of $B_s^0$ and $overline{B}_s^0$ mesons into the $J/psi K^+K^-$ final state are studied in the $K^+K^-$ mass region above the $phi(1020)$ meson in order to determine the resonant substructure and measure the $CP$-violating phase, $phi_s$, the decay width, $Gamma_s$, and the width difference between light and heavy mass eigenstates, $DeltaGamma_s$. A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of $3{rm fb}^{-1}$ produced in 7 and 8 Tev $pp$ collisions at the LHC, collected by the LHCb experiment. The measurement determines $phi_s = 119pm107pm34 {rm , mrad}$. A combination with previous LHCb measurements using similar decays into the $J/psi pi^+pi^-$ and $J/psiphi(1020)$ final states gives $phi_s=1pm37 {rm ,mrad}$, consistent with the Standard Model prediction.
The decay-time-dependent $CP$ asymmetry in $B^{0}_{s}to J/psi K^{+} K^{-}$ decays is measured using proton-proton collision data, corresponding to an integrated luminosity of $1.9,mathrm{fb^{-1}}$, collected with the LHCb detector at a centre-of-mass energy of $13,mathrm{TeV}$ in 2015 and 2016. Using a sample of approximately 117,000 signal decays with an invariant $K^{+} K^{-}$ mass in the vicinity of the $phi(1020)$ resonance, the $CP$-violating phase $phi_s$ is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the $B^{0}_{s}$-$bar{B}^{0}_{s}$ system, $DeltaGamma_s$. The difference of the average $B^{0}_{s}$ and $B^{0}$ meson decay widths, $Gamma_s-Gamma_d$, is determined using in addition a sample of $B^{0} to J/psi K^{+} pi^{-}$ decays. The values obtained are $phi_s = -0.083pm0.041pm0.006,mathrm{rad}$, $DeltaGamma_s = 0.077 pm 0.008 pm 0.003, mathrm{ps^{-1}}$ and $Gamma_s-Gamma_d = -0.0041 pm 0.0024 pm 0.0015,mathrm{ps^{-1}}$, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from $B^{0}_{s}to J/psi pi^{+} pi^{-}$ decays obtained using the same dataset as this analysis, and with previous independent LHCb results.
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