CP violation in Bs to J/psi phi : update from ATLAS

In this talk, the measurement of the Bs → J/psi phi decay parameters using 80.5 fb−1 of integrated luminosity collected with the ATLAS detector from 13 TeV proton–proton collisions at the LHC is presented. The measured parameters include the CP-violating phase phi_s, the width difference DeltaGamma_s between the Bs meson mass eigenstates and the average decay width Gamma_s. Results for phi_s and DeltaGamma_s are also presented as 68% confidence level contours in the phi_s–DeltaGamma_s plane.