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

Chatrchyan S., Khachatryan V., Sirunyan A., Tumasyan A., Adam W., Bergauer T., ...More

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol.714, no.2-5, pp.136-157, 2012 (SCI-Expanded) identifier identifier


The Λ b differential production cross section and the cross section ratio σ(Λ-b)/σ(Λb) are measured as functions of transverse momentum pTΛb and rapidity |y Λb| in pp collisions at s=7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Λ b 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 pTΛb falls faster than that of b mesons. The measured value of σ(Λb)×B(Λb→J/ψΛ) for pTΛb>10 GeV and |y Λb|<2.0 is 1.16±0.06±0.12nb, and the integrated σ(Λ-b)/σ(Λb) ratio is 1.02±0.07±0.09, where the uncertainties are statistical and systematic, respectively. © 2012 CERN.