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Register a new userFirst measurement of the $CP$-violating phase in $B^0_sto J/psi(to e^+e^-)phi$ decays
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A flavour-tagged time-dependent angular analysis of $B^0_sto J/psiphi$ decays is presented where the $J/psi$ meson is reconstructed through its decay to an $e^+e^-$ pair. The analysis uses a sample of $pp$ collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. The $CP$-violating phase and lifetime parameters of the $B^0_s$ system are measured to be $phi_s=0.00pm0.28pm0.07$ rad, $DeltaGamma_s=0.115pm0.045pm0.011$ ps$^{-1}$ and $Gamma_s=0.608pm0.018pm0.012$ ps$^{-1}$ where the first uncertainty is statistical and the second systematic. This is the first time that $CP$-violating parameters are measured in the $B^0_sto J/psiphi$ decay with an $e^+e^-$ pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions.
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We report a measurement of the branching fraction of the decay $B^0_sto J/psi,phi(1020)$, evidence and a branching fraction measurement for $B^0_sto J/psi,f_2(1525)$, and the determination of the total $B^0_sto J/psi,K^+K^-$ branching fraction, including the resonant and non-resonant contributions to the $K^+K^-$ channel. We also determine the $S$-wave contribution within the $phi(1020)$ mass region. The absolute branching fractions are $mathcal{B}[B^0_sto J/psi,phi(1020)]=(1.25 pm 0.07left(mathrm{stat}right)pm 0.08left(mathrm{syst}right)pm 0.22left(f_sright))times 10^{-3}$, $mathcal{B}[B^0_sto J/psi,f_2(1525)]=(0.26pm 0.06left(mathrm{stat}right)pm 0.02left(mathrm{syst}right) pm 0.05left(f_sright))times 10^{-3}$ and $mathcal{B}[B^0_sto J/psi,K^+K^-] = (1.01pm 0.09left(mathrm{stat}right) pm 0.10left(mathrm{syst}right)pm 0.18left(f_sright))times 10^{-3}$, where the last systematic error is due to the branching fraction of $bbar{b}to B^{(*)}_s B^{(*)}_s$. The branching fraction ratio is found to be $mathcal{B}[B^0_sto J/psi,f_2(1525)]/mathcal{B}[B^0_sto J/psi,phi(1020)]=(21.5pm 4.9left(mathrm{stat}right) pm2.6left(mathrm{syst}right))%$. All results are based on a 121.4 fb$^{-1}$ data sample collected at the $Upsilon(5S)$ resonance by the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider.
A first flavour-tagged measurement of the time-dependent CP-violating asymmetry in $B_s^0 to phiphi$ decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between $B_s^0$-$bar{B}_s^0$ mixing and the $b to s bar{s} s $ gluonic penguin decay amplitude. Using a sample of $pp$ collision data corresponding to an integrated luminosity of $1.0; fb^{-1}$ and collected at a centre-of-mass energy of $7 rm TeV$ with the LHCb detector, $880 B_s^0 to phiphi$ signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46, -0.76] rm rad$ at 68% confidence level. The p-value of the Standard Model prediction is 16%.
The mixing-induced CP-violating phase $phi_s$ in ${B}^0_s$ and $overline{B}^0_s$ decays is measured using the $J/psi pi^+pi^-$ final state in data, taken from 3,fb$^{-1}$ of integrated luminosity, collected with the LHCb detector in 7 and 8 TeV centre-of-mass $pp$ collisions at the LHC. A time-dependent flavour-tagged amplitude analysis, allowing for direct CP violation, yields a value for the phase $phi_s=70pm 68pm 8$,mrad. This result is consistent with the Standard Model expectation and previous measurements.
A search for the decays $B^0_sto e^+e^-$ and $B^0to e^+e^-$ is performed using data collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$, $8$ and $13,text{TeV}$, corresponding to integrated luminosities of $1$, $2$ and $2,text{fb}^{-1}$, respectively. No signal is observed. Assuming no contribution from $B^0to e^+e^-$ decays, an upper limit of $mathcal{B}(B^0_sto e^+e^-)<9.4,(11.2)times10^{-9}$ is obtained at $90,(95),%$ confidence level. If no $B^0_sto e^+e^-$ contribution is assumed, a limit of $mathcal{B}(B^0to e^+e^-)<2.5,(3.0)times10^{-9}$ is determined at $90,(95),%$ confidence level. These upper limits are more than one order of magnitude lower than the previous values.
We present a measurement of the CP-violating parameter betas using approximately 6500 $BsJpsiPhi$ decays reconstructed with the CDF,II detector in a sample of $pbar p$ collisions at $sqrt{s}=1.96$ TeV corresponding to 5.2 fb$^{-1}$ integrated luminosity produced by the Tevatron Collider at Fermilab. We find the CP-violating phase to be within the range $betas in [0.02, 0.52] cup [1.08, 1.55]$ at 68% confidence level where the coverage property of the quoted interval is guaranteed using a frequentist statistical analysis. This result is in agreement with the standard model expectation at the level of about one Gaussian standard deviation. We consider the inclusion of a potential $S$-wave contribution to the $Bsto J/psi K^+K^-$ final state which is found to be negligible over the mass interval $1.009 < m(K^+K^-)<1.028 gevcc$. Assuming the standard model prediction for the CP-violating phase betas, we find the Bs decay width difference to be $deltaG = 0.075 pm 0.035,textrm{(stat)} pm 0.006,textrm{(syst)} ps$. We also present the most precise measurements of the Bs mean lifetime $tau(Bs) = 1.529 pm 0.025,textrm{(stat)} pm 0.012,textrm{(syst)}$ ps, the polarization fractions $|A_0(0)|^2 = 0.524 pm 0.013,textrm{(stat)} pm 0.015,textrm{(syst)}$ and $|A_{parallel}(0)|^2 = 0.231 pm 0.014,textrm{(stat)} pm 0.015,textrm{(syst)}$, as well as the strong phase $delta_{perp}= 2.95 pm 0.64,textrm{(stat)} pm 0.07,textrm{(syst)} textrm{rad}$. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.
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