Investigating D⁰ meson production in $p-$Pb collisions at 5.02 TeV with a multi-phase transport model

We study the production of D⁰ meson in p+p and $p-$Pb collisions using the improved AMPT model considering both coalescence and independent fragmentation of charm quarks after the Cronin broadening are included. After a detailed discussion of the improvements implemented in the AMPT model for heavy quark production, we show that the modified AMPT model can provide good description of D⁰ meson spectra in $p-$Pb collisions, the QpPb data at different centrality and RpPb data in both mid- and forward (backward) rapidities. We also studied the effects of nuclear shadowing and parton cascade on the rapidity dependence of D⁰ meson production and RpPb. Our results indicate that having the same strength of the Cronin (i.e δ value) obtained from the mid-rapidity data leads to a considerable overestimation of the D⁰ meson spectra and RpPb data at high pT in the backward rapidity. As a result, the δ is determined via a χ² fitting of the RpPb data across various rapidities. This work lays the foundation for a better understanding of cold-nuclear-matter (CNM) effects in relativistic heavy-ion collisions.