Measurement of the CP-violating phase φs and the B 0s meson decay width difference with B 0s→ J/ψφ decays in ATLAS

Abstract

A measurement of the B0s decay parameters in the B0s → J/ψφ channel using an integrated luminosity of 14.3 fb−1 collected by the ATLAS detector from 8 TeV pp collisions at the LHC is presented. The measured parameters include the CP-violating phase φs, the decay width Γs and the width difference between the mass eigenstates ∆Γs. The values measured for the physical parameters are statistically combined with those from 4.9 fb−1 of 7 TeV data, leading to the following: φs = −0.090 ± 0.078 (stat.) ± 0.041 (syst.) rad ∆Γs = 0.085 ± 0.011 (stat.) ± 0.007 (syst.) ps−1 Γs = 0.675 ± 0.003 (stat.) ± 0.003 (syst.) ps−1. In the analysis the parameter ∆Γs is constrained to be positive. Results for φs and ∆Γs are also presented as 68% and 95% likelihood contours in the φs–∆Γs plane. Also measured in this decay channel are the transversity amplitudes and corresponding strong phases. All measurements are in agreement with the Standard Model predictions.