Measurement of the CP-violating phase $ϕ_s$ in $\overline{B}^0_s\rightarrow J/ψπ^+π^-$ decays

Abstract

The mixing-induced CP-violating phase $ϕ_s$ in ${B}^0_s$ and $\overline{B}^0_s$ decays is measured using the $J/ψπ^+π^-$ final state in data, taken from 3\,fb$^{-1}$ of integrated luminosity, collected with the LHCb detector in 7 and 8 TeV centre-of-mass $pp$ collisions at the LHC. A time-dependent flavour-tagged amplitude analysis, allowing for direct \CP violation, yields a value for the phase $ϕ_s=70\pm 68\pm 8$\,mrad. This result is consistent with the Standard Model expectation and previous measurements.

14 pages, 5 figures