Traces of the nuclear liquid-gas phase transition in the analytic properties of hot QCD

Abstract

The nuclear liquid-gas transition at normal nuclear densities, n ∼ n0 = 0.16 fm −3 , and small temperatures, T ∼ 20 MeV, has a large influence on analytic properties of the QCD grand-canonical thermodynamic potential. A classical van der Waals equation is used to determine these unexpected features due to dense cold matter qualitatively. The existence of the nuclear matter critical point results in thermodynamic branch points, which are located at complex chemical potential values, for T > Tc 20 MeV, and exhibit a moderate model dependence up to rather large temperatures T 100 MeV. The behavior at higher temperatures is studied using the van der Waals hadron resonance gas (vdW-HRG) model. The baryon-baryon interactions have a decisive influence on the QCD thermodynamics close to µB = 0. In particular, nuclear matter singularities limit the radius of convergence r µ B /T of the Taylor expansion in µB/T , with r µ B /T ∼ 2−3 values at T ∼ 140−170 MeV obtained in the vdW-HRG model.

Critical point fluctuations: Finite size and global charge conservation effects

“…The x dependence according to Eqs. (29)- (31), shown by the red lines in Fig. 3, reflects the global N 0 conservation.…”

“…One can then extract κσ 2 gce from experimentally measured κσ 2 and the previously reconstructed Sσ gce using Eq. (31).…”

“…However, they can be estimated (and then corrected for) using the formulas of the subensemble acceptance procedure, Eqs. (29)- (31). It should be noted, however, that the skewness goes to zero at x = 1/2, as this quantity is an asymmetric function of x in the interval [0,1].…”

“…Then, one can use Eqs. (29)- (31) to extract the corresponding GCE values, ω gce , Sσ gce , and κσ 2 gce . Also, as larger systems are closer to the thermodynamic limit, it is preferable to study the most central collisions of heavy ions.…”

“…It was demonstrated [12] that the nuclear CP, i.e., the end point of the liquid-gas transition in the system of interacting nucleons at small T and large μ B , affects the susceptibilities of conserved charges even at μ B = 0 and large T , and limits the radius of convergence of Taylor expansion in μ B /T at μ B = 0 [31]. The sought-after hypothetical chiral QCD CP is expected to produce strong signals in high-order fluctuation measures [2,4,32,33].…”