Open charm production and asymmetry in pNe collisions at $$\sqrt{s_{\scriptscriptstyle {\textrm{NN}}}} = 68.5$$ $$\,\text {Ge\hspace{-1.00006pt}V}

A measurement of $${{D}} ^0$$ D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $${{D}} ^0$$ D 0 mesons is studied with a beam of 2.5 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $$\sqrt{s_{\scriptscriptstyle \text {NN}}} = 68.5\,\,\text {Ge\hspace{-1.00006pt}V} $$ s NN = 68.5 Ge V . The sum of the $${{D}} ^0$$ D 0 and $${\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0$$ D ¯ 0 production cross-section in $$p\text {Ne}$$ p Ne collisions in the centre-of-mass rapidity range $$y^{\star }\in [-2.29, 0]$$ y ⋆ ∈ [ - 2.29 , 0 ] is found to be $$\sigma _{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \,\upmu \text {b}/\text {nucleon}$$ σ D 0 y ⋆ ∈ [ - 2.29 , 0 ] = 48.2 ± 0.3 ± 4.5 μ b / nucleon where the first uncertainty is statistical and the second is systematic. The $${{{D}} ^0}-{{\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0} $$ D 0 - D ¯ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative $$y^{\star }$$ y ⋆ . 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.