Measurement of the CP -violating phase βsJ/ψϕ in Bs0→J/ψϕ decays with the CDF II detector

Le résumé fourni par la source

We present a measurement of the $CP$-violating parameter ${\ensuremath{\beta}}_{s}^{J/\ensuremath{\psi}\ensuremath{\phi}}$ using approximately 6500 ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\phi}$ decays reconstructed with the CDF II detector in a sample of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ corresponding to $5.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ integrated luminosity produced by the Tevatron collider at Fermilab. We find the $CP$-violating phase to be within the range ${\ensuremath{\beta}}_{s}^{J/\ensuremath{\psi}\ensuremath{\phi}}\ensuremath{\in}[0.02,0.52]\ensuremath{\cup}[1.08,1.55]$ 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 ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}{K}^{\ensuremath{-}}$ final state which is found to be negligible over the mass interval $1.009<m({K}^{+}{K}^{\ensuremath{-}})<1.028\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. Assuming the standard model prediction for the $CP$-violating phase ${\ensuremath{\beta}}_{s}^{J/\ensuremath{\psi}\ensuremath{\phi}}$, we find the ${B}_{s}^{0}$ decay width difference to be $\ensuremath{\Delta}{\ensuremath{\Gamma}}_{s}=0.075\ifmmode\pm\else\textpm\fi{}0.035(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.006(\mathrm{syst})\text{ }\text{ }{\mathrm{ps}}^{\ensuremath{-}1}$. We also present the most precise measurements of the ${B}_{s}^{0}$ mean lifetime $\ensuremath{\tau}({B}_{s}^{0})=1.529\ifmmode\pm\else\textpm\fi{}0.025(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.012(\mathrm{syst})\text{ }\text{ }\mathrm{ps}$, the polarization fractions $|{A}_{0}(0){|}^{2}=0.524\ifmmode\pm\else\textpm\fi{}0.013(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.015(\mathrm{syst})$ and $|{A}_{\ensuremath{\parallel}}(0){|}^{2}=0.231\ifmmode\pm\else\textpm\fi{}0.014(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.015(\mathrm{syst})$, as well as the strong phase ${\ensuremath{\delta}}_{\ensuremath{\perp}}=2.95\ifmmode\pm\else\textpm\fi{}0.64(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{syst})\text{ }\text{ }\mathrm{rad}$. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.