DISCRETE 2012: CP violation at ATLAS

A measurement of the decay $B_s \rightarrow J/\psi (\mu^+ \mu^-) \phi(K^+ K^-)$ in made extracting the decay parameters, including the $CP$-violating weak phase $\phi_s$ and the decay width difference $\Delta\Gamma_s$ from a dataset of 4.9 $fb^{-1}$ of integrated luminosity collected in 2011 by the ATLAS detector at the LHC. The measured parameters are consistent with the world average values and theoretical expectations, in particular $\phi_s$ is within 1 $\sigma$ of the expected value in the Standard Model. This analysis is published in the Journey of High Energy physics.