Resonances and $CP$ violation in $B_s^0$ and $\overline{B}_s^0 \to J/\psi K^+K^-$ decays in the mass region above the $\phi(1020)$

Abstract

The decays of $B_s^0$ and $\overline{B}^0_s$ mesons into the $J/\psi K^+K^-$ final state are studied in the $K^+K^-$ mass region above the $\phi(1020)$ meson in order to determine the resonant substructure and measure the $CP$-violating phase, $\phi_s$ , the decay width, $\Gamma_s$ , and the width difference between light and heavy mass eigenstates, $\Delta\Gamma_s$. A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of 3 fb$^{−1}$ produced in 7 and 8 TeV $pp$ collisions at the LHC, collected by the LHCb experiment. The measurement determines $\phi_s = 119 \pm 107 \pm 34$ mrad. A combination with previous LHCb measurements using similar decays into the $J/\psi\pi^+\pi^-$ and $J/\psi\phi(1020)$ final states gives $\phi_s = 1 \pm 37$ mrad, consistent with the Standard Model prediction.