Applicability of Hydrodynamics in Hadronic Phase of Heavy-Ion Collisions

Abstract

The hadronic phase and its dynamics in relativistic heavy-ion collisions are topics of immense discussion. The hadronic phase contains various massive hadrons with an abundance of the lightest hadron, i.e., $\pi$-mesons (pions). In this paper, we consider that pions are in thermal equilibrium in the hadronic phase and use second-order viscous hydrodynamics for a medium of massive pions to obtain its expansion to the boundary of the kinetic freeze-out. We achieve the kinetic freeze-out boundary with the Knudsen number $Kn>1$ limit. When this condition is met, hydrodynamics expansion breaks down, and the mean free path becomes sufficiently large in comparison with the system size so that the particle yields are preserved. Further, we investigate the effect of the massive fluid on the resonance particle yields, including re-scattering and regeneration, along with the natural decay widths of the resonances. The resonances can play an essential role in determining the characteristics of the hadronic phase as they have sufficiently small lifetimes, which may be comparable to the hadronic phase lifetime. In the current study, we predict the hadronic phase lifetime, which is further used to determine the $K^{\ast }(892{)}^0/K$, $\varphi (1020)/K$, and $\rho (770{)}^0/\pi$ yield ratios at the kinetic freeze-out. We calculate these ratios as a function of charged particle multiplicity and transverse momentum and compare the findings with experimental data. Our calculations qualitatively agree with the experimental data, indicating a possible hydrodynamical evolution of the hadronic phase.

13 pages and 6 captioned figures. Same as the published version

References in corpus (12)

• Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics
• The order of the quantum chromodynamics transition predicted by the standard model of particle physics
• The equation of state in (2+1)-flavor QCD
• Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
• Bayesian estimation of the specific shear and bulk viscosity of the quark-gluon plasma with additional flow harmonic observables
• Hadron Resonance Gas Equation of State from Lattice QCD
• New constraints for QCD matter from improved Bayesian parameter estimation in heavy-ion collisions at LHC
• Bottomium suppression in PbPb collisions at LHC energies
• Charmonium suppression in ultra-relativistic proton-proton collisions at LHC energies: A hint for QGP in small systems
• Studying re-scattering effect in heavy-ion collision through $K^{\ast }$ Production
• Exploring the effect of hadron cascade-time on particle production in Xe+Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV through a multi-phase transport model
• Fluidity of the system produced in relativistic pp and heavy-ion collisions: Hadron resonance gas model approach