Measurement of the CP-violating phase ${\varphi }_s$ in ${\overline{B}}_s^0\to J/\psi {\pi }^{+}{\pi }^{-}$ decays

Abstract

The mixing-induced CP-violating phase ${\varphi }_s$ in $B_s^0$ and ${\overline{B}}_s^0$ decays is measured using the $J/\psi {\pi }^{+}{\pi }^{-}$ 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 ${\varphi }_s=70\pm 68\pm 8$\,mrad. This result is consistent with the Standard Model expectation and previous measurements.

Comments: 14 pages, 5 figures