Rapidity and transverse momentum dependence of inclusive J/ψ production in pp collisions at √s = 7 TeV

Abstract The ALICE experiment at the LHC has studied inclusive J / ψ production at central and forward rapidities in pp collisions at s = 7 TeV . In this Letter, we report on the first results obtained detecting the J / ψ through the dilepton decay into e + e − and μ + μ − pairs in the rapidity ranges | y | 0.9 and 2.5 y 4 , respectively, and with acceptance down to zero p T . In the dielectron channel the analysis was carried out on a data sample corresponding to an integrated luminosity L int = 5.6 nb − 1 and the number of signal events is N J / ψ = 352 ± 32 ( stat. ) ± 28 ( syst. ) ; the corresponding figures in the dimuon channel are L int = 15.6 nb − 1 and N J / ψ = 1924 ± 77 ( stat. ) ± 144 ( syst. ) . The measured production cross sections are σ J / ψ ( | y | 0.9 ) = 10.7 ± 1.0 ( stat. ) ± 1.6 ( syst. ) − 2.3 + 1.6 ( syst.pol. ) μb and σ J / ψ ( 2.5 y 4 ) = 6.31 ± 0.25 ( stat. ) ± 0.76 ( syst. ) − 1.96 + 0.95 ( syst.pol. ) μb . The differential cross sections, in transverse momentum and rapidity, of the J / ψ were also measured.