Study of Bs0 → J/ψπ+π−K+K− decays

Abstract

The decays Bs0$$ {\mathrm{B}}{\mathrm{s}}^0 $$ → J/ψπ+π−K+K− are studied using a data set corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The decays Bs0$$ {\mathrm{B}}{\mathrm{s}}^0 $$ → J/ψK∗0K¯∗0$$ \mathrm{J}/{\uppsi \mathrm{K}}^{\ast 0}{\overline{\mathrm{K}}}^{\ast 0} $$ and Bs0$$ {\mathrm{B}}{\mathrm{s}}^0 $$ → χc1(3872)K+K−, where the K+K−pair does not originate from a ϕ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate χc1(3872)ϕ, J/ψK∗0K¯∗0$$ \mathrm{J}/{\uppsi \mathrm{K}}^{\ast 0}{\overline{\mathrm{K}}}^{\ast 0} $$, ψ(2S)ϕ and χc1(3872)K+K− states are reported. A structure, denoted as X(4740), is observed in the J/ψϕ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to bemX4740=4741±6±6MeV/c2,ΓX4740=53±15±11MeV,$$ {\displaystyle \begin{array}{c}{m}{\mathrm{X}(4740)}=4741\pm 6\pm 6\kern0.5em \mathrm{MeV}/{c}^2,\ {}{\Gamma}{\mathrm{X}(4740)}=53\pm 15\pm 11\kern0.5em \mathrm{MeV},\end{array}} $$where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the Bs0$$ {\mathrm{B}}{\mathrm{s}}^0 $$ meson is performed and gives a value ofmBs0=5366.98±0.07±0.13MeV/c2.$$ {m}{{\mathrm{B}}{\mathrm{s}}^0}=5366.98\pm 0.07\pm 0.13\kern0.5em \mathrm{MeV}/{c}^2. $$