urement of the branching ratio Γ(Λ0b→ψ(2S)Λ0)/Γ(Λ0b→J/ψΛ0) with the ATLAS detector

F. MONTICELLI; ATLAS COLLABORATION

PHYSICS LETTERS B

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 1 p. 1 - 20

0370-2693

An observation of the Λb0→ψ(2S)Λ0 decay and a comparison of its branching fraction with that of the Λb0→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 Λb0 baryons are reconstructed with transverse momentum pT>10 GeV and pseudorapidity |η|<2.1 . The measured branching ratio of the Λb0→ψ(2S)Λ0 and Λb0→J/ψΛ0 decays is Γ(Λb0→ψ(2S)Λ0)/Γ(Λb0→J/ψΛ0)=0.501±0.033(stat)±0.019(syst) , lower than the expectation from the covariant quark model.