Study of B0s → J/ψπ+π−K+K− decays

Abstract

The decays B0s → 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 B0s → J/ψK∗0K¯¯¯¯∗0 and B0s → 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

, 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 be mX(4740)=4741±6±6MeV/c2,ΓX(4740)=53±15±11MeV,

where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the B0s

meson is performed and gives a value of

mB0s=5366.98±0.07±0.13MeV/c2.