Impact of nucleon mass shift on the freeze-out process

Abstract

The freeze out of a massive nucleon gas through a finite layer with time-like normal is studied. The impact of in-medium nucleon mass shift on the freeze out process is investigated. A considerable modification of the thermodynamical variables temperature, flow-velocity, energy density and particle density has been found. Due to the nucleon mass shift the freeze out particle distribution functions are changed noticeably in comparison with evaluations, which use vacuum nucleon mass.

Covariant description of kinetic freeze-out through a finite time-like layer

“…A successful application of this model was already used to study the impact of nucleon mass shift on the freeze out process [12]. This analysis will be carried forward to calculate the impact of mass shift on other particles, such as pions and kaons, which will help us study the effect of mass shift on two-particle correlations.…”

“…For a thorough analysis of this approach, see Refs. [1,12] and the Appendix. Here we mention that in our calculations we use only one type of particles, namely massless pions, therefore the chemical composition of our system remains unchanged during the kinetic FO.…”

Pion mass shift and the kinetic freeze-out process

“…(15) see footnote 3 in [34], and for eq. ( 16) see also the remarks in the Appendix A of [31] 3 Freeze Out Process within a finite time-like layer…”

“…So far, the impact of in-medium modifications of hadrons on the FO process has been considered only in Refs. [29,30,31]. In our investigation we will apply this recently developed FO model and consider a kinetic FO scenario through a finite time-like layer to study the impact of in-medium pion mass modification on the FO process.…”

Entropy production at freeze-out from dissipative fluids

“…The properties of matter change considerably in a small spacetime domain, characterized by a time-scale, τ ′ (τ ), which governs the process. Here, we recall the assumption for the escape rate [21,22], which characterizes the freezeout of matter in finite time, L, the proper time interval between two parallel hypersurfaces, where the continuous freeze-out of matter starts at τ 0 and ends at τ 0 + L, thus…”