First Measurement of Charm Production in its Fixed-Target Configuration at the LHC

Abstract

The first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of J / ψ and D 0 mesons is studied with beams of protons of different energies colliding with gaseous targets of helium and argon with nucleon-nucleon center-of-mass energies of √ s NN = 86.6 and 110.4 GeV, respectively. The J / ψ and D 0 production cross sections in p He collisions in the rapidity range [2, 4.6] are found to be σ J / ψ = 652 ± 33 ( stat ) ± 42 ( syst ) nb / nucleon and σ D 0 = 80.8 ± 2.4 ( stat ) ± 6.3 ( syst ) μ b / nucleon , where the first uncertainty is statistical and the second is systematic. No evidence for a substantial intrinsic charm content of the nucleon is observed in the large Bjorken- x region.