Evidence for the decay X(3872) →ψ(2S)γ

Abstract

Evidence for the decay mode X(3872) →ψ(2S)γin B+→X(3872)K+decays is found with a sig-nificance of 4.4 standard deviations. The analysis is based on adata sample of proton–proton collisions, corresponding to an integrated luminosity of3fb−1, collected with the LHCb detector, at centre-of-mass energies of 7and8TeV. The ratio of the branching fraction of the X(3872) →ψ(2S)γdecay to that of the X(3872) →J/ψγdecay is measured to be B(X(3872)→ψ(2S)γ) B(X(3872)→J/ψγ) = 2.46± 0.64±0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support apureD¯ D∗molecular interpretation of the X(3872)state.