Simple solution to the Strangeness Horn description puzzle

Abstract

We propose to use the thermal model with the multi-component hard-core radii to describe the hadron yield ratios from the low AGS to the highest RHIC energies. It is demonstrated that the variation of the hard-core radii of pions and kaons enable us to drastically improve the fit quality of the measured mid-rapidity data and for the first time to completely describe the Strangeness Horn behavior as the function of the energy of collision without spoiling the fit quality of other ratios. The best global fit is found for the vanishing hard-core radius of pions and for the hard-core radius of kaons being equal to 0.35 fm, whereas the hard-core radius of all other mesons is fixed to 0.3 fm and that one of baryons is fixed to 0.5 fm.It is argued that the multi-component hadron resonance gas model opens us a principal possibility to determine the second virial coefficients of hadron-hadron interaction. I. INTRODUCTIONThe hadron resonance gas model 1 [1, 2] is the only theoretical tool allowing us to extract information about the chemical freeze-out (FO) stage of the relativistic heavy ion collisions. Although its systematic application to the experimental data description began about fifteen years ago [3], many features of this model are not well studied [4,5]. Thus, very recently in a critical analysis of the hadron resonance gas model [5] it was shown that for the description of the hadron multiplicities the baryon charge conservation and the isospin conservation, used in one of the most successful versions of this model [1], should be essentially modified, whereas for the description of the hadron yield ratios these conservation laws are not necessary at all. Although the discussion about the reliable chemical FO criterion has a long history [1,6], only recently it was demonstrated that none of the previously suggested chemical FO criteria, including the most popular one of constant energy per particle E/N 1.1 GeV [6], is robust [5], if the realistic particle table with the hadron masses up to 2.5 GeV is used. At the same time in [5] it was shown that despite an essential difference with the approach used in [1], the both versions of the hadron resonance gas * Electronic address: Bugaev@th.physik.uni-frankfurt.de † Electronic address: Dimafopf@gmail.com ‡ Electronic address: Sorin@theor.jinr.ru § Electronic address: Gennady.Zinovjev@cern.ch 1We apologize for not quoting even the major works on this model which are well known, but the list is so long that we have to choose just the papers strictly related to our discussion.

Strangeness Enhancement at the Hadronic Chemical Freeze-Out

“…Further we analyzed the data set at the highest AGS energy ( √ = 4.9 AGeV or = 10.7 AGeV). Similarly to [4], here we analyzed only the NA49 mid-rapidity data [19][20][21][22][23][24] The fit criterion is a minimization of…”

“…It is the model developed in [4,[7][8][9][10]. The hadron interaction is taken into account via the hardcore repulsion whose radii have different values for pions , kaons , other mesons and baryons .…”

“…The hadron yields measured in heavy ion collisions are traditionally analyzed by the Hadron Resonance Gas Model (HRGM) [1][2][3][4]. Its main assumption is an existence of the thermal equilibrium in the system under consideration, which is strongly supported by an excellent coincidence of experimental and theoretical yields of the hadrons built up from and quarks.…”

“…[6] are consistent with = 1. In order to resolve the latter problem, we apply the most successful version of the HRGM with multicomponent hard-core repulsion [4,[7][8][9][10] to describe 111 independent hadron yield ratios measured at 14 values of the center of mass collision energy √ in the interval from 2.7 GeV to 200 GeV.…”

Nuclear and hadron matter equation of state within the induced surface tension approach

“…As one can see from left panel on After fixing the parameter α one can apply the IST EoS to study the properties of the hadron resonance gas and the ones of nuclear matter. The new EoS is essentially more effective compared to the traditional multicomponent Hadron Resonance Gas Model (MHRGM) [11][12][13][14] and traditional Statistical Multifragmentation Model (SMM) [15][16][17][18], since it can be easily used for any number of independent hard-core radii.…”