Measurement of prompt J/ψ and beauty hadron production cross sections at mid-rapidity in pp collisions at TeV

Abstract

The ALICE experiment at the LHC has studied J/ψ production at mid-rapidity in pp collisions at TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L_int = 5.6 nb⁻¹. The fraction of J/ψ from the decay of long-lived beauty hadrons was determined for J/ψ candidates with transverse momentum p_t> 1.3 GeV/c and rapidity |y| < 0.9. The cross section for prompt J/ψ mesons, i.e. directly produced J/ψ and prompt decays of heavier charmonium states such as the ψ(2S) and χ_c resonances, is σ_{prompt J/ψ} (p_t> 1.3 GeV/c, |y| < 0.9) = 8.3 ± 0.8 (stat.) ± 1.1 (syst.) (syst. pol.) μb. The cross section for the production of b-hadrons decaying to J/ψ with p_t> 1.3 GeV/c and |y| < 0.9 is (p_t > 1.3 GeV/c, |y| < 0.9) = 1.46 ± 0.38 (stat.) (syst.) μb. The results are compared to QCD model predictions. The shape of the p_t and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the pair total cross section and dσ/dy at mid-rapidity.