Speaker
Description
A measurement of the $B_S^0\rightarrow J/\psi\phi$ decay parameters using $80~\mathrm{fb}^{-1}$ of integrated luminosity collected with the ATLAS detector from $13~\mathrm{TeV}$ proton-proton collisions at the LHC is presented. The measured parameters include the CP-violating phase $\phi_S$, the width difference $\Delta\Gamma_S$ between the $B_S^0$ meson mass eigenstates and the average decay width $\Gamma_S$. The values measured for the physical parameters are combined with those from $19.2~\mathrm{fb}^{-1}$ of $7~\mathrm{TeV}$ and $8~\mathrm{TeV}$ data, leading to the following:
$\phi_S=-0.087\pm0.036~(\mathrm{stat.})\pm0.021~(\mathrm{syst.})~\mathrm{rad}$
$\Delta\Gamma_S=0.0657\pm0.0043~(\mathrm{stat.})\pm0.0037~(\mathrm{syst.})~\mathrm{ps}^{-1}$
$\Gamma_S=0.6703\pm0.0014~(\mathrm{stat.})\pm0.0018~(\mathrm{syst.})~\mathrm{ps}^{-1}$
Results for $\phi_S$ and $\Delta\Gamma_S$ are also presented as $68\%$ confidence level contours in the $\phi_S-\Delta\Gamma_S$ plane. Furthermore, the transversity amplitudes and corresponding strong phases are measured. $\phi_S$ and $\Delta\Gamma_S$ measurements are in agreement with the Standard Model predictions.
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