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

Abstract

Evidence for the decay mode X(3872) → ψ(2S)γ in 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 of 3 fbthe X(3872), collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872) → ψ(2S)γ decay to that of the X(3872) → J/ψγ decay 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 a pure DD* molecular interpretation of the X(3872)state.