  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.

High Energy Physics - Experiment