Measurement of the branching ratio Gamma(Lambda(0)(b) -> Psi(2S)Lambda(0))/Gamma(Lambda(0.)(b) -> J/Psi Lambda(0)) with the ATLAS detector

An observation of the 0 b → ψ(2S)0 decay and a comparison of its branching fraction with that of the 0 b → J/ψ0 decay has been made with the ATLAS detector in proton–proton collisions at √s = 8 TeV at the LHC using an integrated luminosity of 20.6 fb−1. The J/ψ and ψ(2S) mesons are reconstructed in their decays to a muon pair, while the 0 → pπ− decay is exploited for the 0 baryon reconstruction. The 0 b baryons are reconstructed with transverse momentum pT > 10 GeV and pseudorapidity |η| < 2.1. The measured branching ratio of the 0 b → ψ(2S)0 and 0 b → J/ψ0 decays is (0 b → ψ(2S)0)/(0 b → J/ψ0) = 0.501 ± 0.033(stat) ± 0.019(syst), lower than the expectation from the covariant quark model. © 2015 CERN for the benefit of the ATLAS Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.