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

09 April 2019

Abstract: The first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of $J/\psi$ 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 $\sqrt{{s}_{\mathrm{NN}}}=86.6$ and 110.4 GeV, respectively. The $J/\psi$ and ${D}^{0}$ production cross sections in $p\mathrm{He}$ collisions in the rapidity range [2, 4.6] are found to be ${\sigma }_{J/\psi }=652±33\left(\text{stat}\right)±42\left(\text{syst}\right)\text{}\text{}\text{}\mathrm{nb}/\text{nucleon}$ and ${\sigma }_{{D}^{0}}=80.8±2.4\left(\text{stat}\right)±6.3\left(\text{syst}\right)\text{}\text{}\mu b/\text{nucleon}$, 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.

Published in: Physical Review Letters 122 (2019)