Measurement of the $CP$-violating phase ${\varphi }_s$ from $B_s^0\to J/\psi {\pi }^{+}{\pi }^{-}$ decays in 13 TeV $pp$ collisions

LHCb Collaboration, R. Aaij, C. Abellán Beteta +844

Decays of $B_s^0$ and $\overline{B}{}_s^0$ mesons into $J/\psi {\pi }^{+}{\pi }^{-}$ final states are studied in a data sample corresponding to 1.9 fb${}^{-1}$ of integrated luminosity collect…