An observation of the Λb 0→ψ(2S)Λ0 decay and a comparison of its branching fraction with that of the Λb 0→J/ψΛ0 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 Λ0→pπ− decay is exploited for the Λ0 baryon reconstruction. The Λb 0 baryons are reconstructed with transverse momentum pT>10 GeV and pseudorapidity |η|<2.1. The measured branching ratio of the Λb 0→ψ(2S)Λ0 and Λb 0→J/ψΛ0 decays is Γ(Λb 0→ψ(2S)Λ0)/Γ(Λb 0→J/ψΛ0)=0.501±0.033(stat)±0.019(syst), lower than the expectation from the covariant quark model.
|Number of pages||18|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - 17 Dec 2015|