Hadronic entropy enhancement and low density QGP

Abstract

Recent studies show that for central collisions the rising of the incident energy from AGS to RHIC decreases the value of the chemical potential in the Hadron-QGP phase diagram. Thus, the formation of QGP at RHIC energies in central collisions may be expected to occur at very small values of the chemical potential. Using many different relativistic mean-field hadronic models (RMF) at this regime we show that the critical temperature for the Hadron-QGP transition is hadronic model independent. We have traced back the reason for this and conclude that it comes from the fact that the QGP entropy is much larger than the hadronic entropy obtained in all the RMF models. We also find that almost all of these models present a strong entropy enhancement in the hadronic sector coming from the baryonic phase transition to a nucleon-antinucleon plasma. This result is in agreement with the recent data obtained in the STAR collaboration at RHIC where it was found a rich proton-antiproton matter.

Hadron production in non-linear relativistic mean field models

“…This situation repeats for the chemical potential fitting (µ = 33.27−32.51 MeV). It is important to mention at this point that in these models the hadronic phase transition regions occur at temperatures T > 180 MeV [12], higher than the freeze-out temperature we found here.…”

“…In this way, they are natural tools to look for QGP signatures. Different models have been used to improve the understanding of the QGP-hadronic matter phase transition [8,9,10,11,12]. The use of thermal models to describe hadronic collision spectra has also been considered [13,14].…”

“…At high energy, it can describe dynamically the evolution from the hadronic fireball starting scenario to the chemical freeze-out in which the baryons and the light mesons populate the gas. One of the advantages of using relativistic quantum-hadronic models is that they can also describe the already mentioned QGP-hadronic matter phase transition as the chemical potential increases [11,12]. The physics of the hadronic models at high temperature is very rich and its behavior has been well investigated for zero chemical potential [30].…”

Critical amplitudes and mass spectrum of the 2d Ising model in a magnetic field

“…In this paper we shall address this problem. We shall show that Zamolodchikov's proposal (and the calculations of [10]) is correct also in the case of the 2d Ising spin model and that the apparent disagreement was due to the fact that it is very difficult to extract a complex spectrum from a multiexponential fit to the spin-spin correlator. We have been prompted to this explanation by another example that we recently studied, in which exactly the same phenomenon happens: the 3d Ising model [11].…”

“…The explanation suggested in [8,9] was that probably the higher masses had a negligible overlap amplitude with the spin operator. However, later, in [10] these overlaps were evaluated explicitly in the S-matrix framework and turned out to be of the same order of magnitude as the overlap with the lowest mass state.…”