Emergence of New Systematics for Open Charm Production in High Energy Collisions

We present the production systematics of open charm hadron yields in high-energy collisions and their description based on the Statistical Hadronization Model of charm (SHMc). The rapidity density of $D^0, D^+, D^{*+}, D_s^+$ mesons and $\Lambda_c^+$ baryons in heavy ion and proton-proton collisions is analyzed for different collision energies and centralities. The SHMc is extended to open charm production in minimum-bias and high-multiplicity pp collisions. In this context, we use the link established in [1,2], between the rapidity density of open charm hadron yields, $dN_i/dy$, and the rapidity density of charm-anticharm quark pairs, $dN_{c\bar c}/dy$. We demonstrate that, in pp, pA and AA collisions, $dN_i/dy$ scales in leading order with $dN_{c\bar c}/d\eta$ and for open charm mesons, $D^0,D^+$ and $D^{*+}$ the slope coefficient is quantified by the appropriate thermal density ratio calculated in the SHMc at the chiral crossover temperature, $T_c=156.5$ MeV. The slope coefficient for $dN_{\Lambda_c^+}/dy$ differs at $T_c$ by a factor of $1.97\pm 0.14$ which is attributed to missing charmed-baryon resonances in the PDG. It is also shown that $dN_i/dy$ exhibits power-law scaling with the charged-particle pseudo-rapidity density in high energy collisions and within uncertainties. Furthermore, presently available data on different ratios of open charm rapidity densities in high-energy collisions are independent of collision energy and system size, as expected in the SHMc.