Open charm production and asymmetry in $p$Ne collisions at $\sqrt{s_{\scriptscriptstyle\rm NN}} =$ 68.5 GeV

TL;DR

This paper reports on the measurement of $D^0$ meson production and asymmetry in proton-neon collisions at 68.5 GeV, providing new insights into charm production mechanisms in fixed-target experiments.

Contribution

It presents the first measurement of $D^0$ production cross-section and asymmetry in $p$Ne collisions at this energy, comparing data with various theoretical models including intrinsic charm and recombination effects.

Findings

Measured $D^0$ production cross-section: 48.2 μb/nucleon.

Observed a trend towards negative $D^0-{ar D}^0$ asymmetry at large negative rapidity.

Models with 1% intrinsic charm and 10% recombination better fit the data.

Abstract

A measurement of $D^0$ meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $D^0$ mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{\rm NN}}$ = 68.5 GeV. The sum of the $D^0$ and ${\overline D^0}$ production cross-section in $p$Ne collisions in the centre-of-mass rapidity range $y^{\star}\in [-2.29, 0]$ is found to be $\sigma_{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \,\mu\textrm{b/nucleon}$ where the first uncertainty is statistical and the second is systematic. The $D^0-{\overline D^0}$ production asymmetry is also evaluated and suggests a trend towards negative values at large negative $y^{\star}$. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1$\%$ intrinsic charm and 10$\%$ recombination contributions better describe the data than the other models considered.