Measurement of the Λb cross section and the Λb to Λb ratio with J/ψΛ decays in pp collisions at √s = 7 TeV

Abstract

The Λb differential production cross section and the cross section ratio σ(Λb)/σ(Λb) are measured as functions of transverse momentum pΛb T and rapidity |yΛb | in pp collisions at √s = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Λb decays reconstructed in the exclusive final state J/ψΛ, with the subsequent decays J/ψ → μ+μ− and Λ → pπ, using a data sample corresponding to an integrated luminosity of 1.9 fb−1. The product σ(Λb) × B(Λb → J/ψΛ) versus pΛb T falls faster than that of b mesons. The measured value of σ(Λb) × B(Λb → J/ψΛ) for pΛb T > 10 GeV and |yΛb | < 2.0 is 1.16 ± 0.06 ± 0.12 nb, and the integrated σ(Λb)/σ(Λb) ratio is 1.02 ± 0.07 ± 0.09, where the uncertainties are statistical and systematic, respectively.