Multiplicity, Transverse Momentum and Pseudorapidity Dependence of Freeze-Out Parameters for Open-Charm Hadrons in Hadronic Collisions at LHC Energy

Abstract

Heavy quarks (charm and beauty) act as better probes in understanding the formation and evolution of the QCD medium in the ultra-relativistic heavy-ion collisions because of their heavy mass and large relaxation time compared to QGP (quark-gluon plasma) lifetime. Possible thermalization of charm quarks is observed in small systems like proton+proton (pp) collisions by studying charm-hadrons, namely D0 and Λc+. With this enthusiasm, we have studied the freeze-out scenarios of D0 and Λc+ in a pp collisions at s = 13 TeV using a pQCD-based framework called PYTHIA8. In this work, the production dynamics of open-charm hadrons are studied as a function of event multiplicity (dNchdη), transverse momentum spectra (pT) and pseudorapidity (η). The pT-spectra are analyzed with thermodynamically consistent non-extensive Tsallis distribution function. The effective temperature (T) and non-extensive parameter (q) have been studied as a function of charged-particle multiplicity, transverse momentum, and pseudorapidity. We observed that T increases with (dNchdη) and decreases with (η) while the non-extensive parameter increases for both the cases, when we consider heavy-flavors. Further, it is observed that the behaviour of T and q with transverse momentum depends explicitly on the final state charged-particle multiplicity. Along with these two parameters T and q, a correlation between these initial state effects and final state effects is observed through the number of multi-partonic interactions (nMPI) and Knudsen number. Possible thermalization in small collision systems and applicability of hydrodynamics are explored. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.