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

A bstract 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 *+ , $$ {D}_s^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> mesons and $$ {\Lambda}_c^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> 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, $$ d{N}_{c\overline{c}}/ dy $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>d</mml:mi> <mml:msub> <mml:mi>N</mml:mi> <mml:mrow> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:mi>dy</mml:mi> </mml:math> . We demonstrate that, in pp, pA and AA collisions, dN i / dy scales in leading order with $$ d{N}_{c\overline{c}}/ d\eta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>d</mml:mi> <mml:msub> <mml:mi>N</mml:mi> <mml:mrow> <mml:mi>c</mml:mi> <mml:mover> <mml:mi>c</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:mi>dη</mml:mi> </mml:math> 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 $$ d{N}_{\Lambda_c^{+}}/ dy $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>d</mml:mi> <mml:msub> <mml:mi>N</mml:mi> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:msub> <mml:mo>/</mml:mo> <mml:mi>dy</mml:mi> </mml:math> 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.