Emergence of new systematics for open charm production in high energy collisions

Abstract

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 D⁰, 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, \( d{N}_{c\overline{c}}/ dy \). We demonstrate that, in pp, pA and AA collisions, dN_i/dy scales in leading order with \( d{N}_{c\overline{c}}/ d\eta \) and for open charm mesons, D⁰, 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 \( d{N}_{\Lambda_c^{+}}/ dy \) differs at T_c by a factor of 1.97 ± 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.