Exploring a possible origin of the QCD critical endpoint

Bugaev, K. A.; Petrov, V. K.; Zinovjev, G.

doi:10.1134/s1063778813020063

Cited by 6 publications

(15 citation statements)

References 30 publications

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“…We note that Eqs. (21) and (26) were used, respectively, to evaluate the density of baryons and point-like pions for a comparison between the IST EoS and the EoS given by (7). Figure 4: Chemical freeze-out parameters of the IST EoS (circles) are compared to the ones found within the HRGM with multicomponent hard-core repulsion (squares) [17].…”

Section: Necessary Formalismmentioning

confidence: 99%

“…for packing fractions η = all hadrons ρ h V h ≤ 0.11 [24] where V h is the eigenvolume of hadron h and ρ h is its particle number density. It is also necessary to note that the HRGM is the discrete part of the mass-volume spectrum of quark-gluon bag model with surface tension which has a tricritical [25] or a critical [26] endpoint. The quark-gluon bag model with surface tension model allows one to describe the properties of strongly interacting matter at high energy densities.…”

Section: Introductionmentioning

confidence: 99%

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Hadron resonance gas model with induced surface tension

et al. 2018

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Here we present a physically transparent generalization of the multicomponent Van der Waals equation of state in the grand canonical ensemble. For the one-component case the third and fourth virial coefficients are calculated analytically. It is shown that an adjustment of a single model parameter allows us to reproduce the third and fourth virial coefficients of the gas of hard spheres with small deviations from their exact values. A thorough comparison of the compressibility factor and speed of sound of the developed model with the one and two component Carnahan-Starling equation of state is made. It is shown that the model with the induced surface tension is able to reproduce the results of the Carnahan-Starling equation of state up to the packing fractions 0.2-0.22 at which the usual Van der Waals equation of state is inapplicable. At higher packing fractions the developed equation of state is softer than the gas of hard spheres and, hence, it breaks causality in the domain where the hadronic description is expected to be inapplicable. Using this equation of state we develop an entirely new hadron resonance gas model and apply it to a description of the hadron yield ratios measured at AGS, SPS, RHIC and ALICE energies of nuclear collisions. The achieved quality of the fit per degree of freedom is about 1.08. We confirm that the strangeness enhancement factor has a peak at low AGS energies, while at and above the highest SPS energy of collisions the chemical equilibrium of strangeness is observed. We argue that the chemical equilibrium of strangeness, i.e. γ s 1, observed above the center of mass collision energy 4.3 GeV may be related to the hadronization of quark gluon bags which have the Hagedorn mass spectrum, and, hence, it may be a new signal for the onset of deconfinement.

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Section: Necessary Formalismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hadron resonance gas model with induced surface tension

et al. 2018

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“…Since the moment of the hadron bags model formulation [2] its original framework was greatly extended and now we have a variety of exactly solvable statistical models which describe the deconfinement phase transition and a cross-over. For instance, the quark gluon bag with surface tension model (QGBSTM) is able to describe the tricritical [6-9] and critical endpoint [10,11] using the mechanism which is typical for ordinary liquids. In Ref.…”

mentioning

confidence: 99%

“…However, the two key questions, namely where (at what energies) and how can one observe the QG bag formation, did not get the definite answers during these almost four decades passed since the MIT Bag model formulation. At the same time a discrete part of the hadronic mass spectrum of the advanced followers [6][7][8][9][10][11][12][13][14][15] of the MIT Bag model which is known as the hadron resonance gas model (HRGM) [19][20][21][22][23][24][25] became a precise tool to extract the thermodynamic quantities at the moment of chemical freeze-out (FO). The latter is the moment at which the inelastic collisions cease to exist simultaneously for all sorts of particles.…”

mentioning

confidence: 99%

Non-Smooth Chemical Freeze-Out and Apparent Width of Wide Resonances and Quark Gluon Bags in a Thermal Environment

Bugaev

Ivanytskyi²,

Oliinychenko³

et al. 2015

Ukr. J. Phys.

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Abstract. Here we develop the hadron resonance gas model with the Gaussian width of hadron resonances. This model allows us to treat the usual hadrons and the quark gluon bags on the same footing and to study the stability of the results obtained within different formulations of the hadron resonance gas model. In this work we perform a successful fit of 111 independent hadronic multiplicity ratios measured for the center of mass collision energies √ s N N = 2.7-200 GeV. Also we demonstrate that in a narrow range of collision energy √ s N N = 4.3-4.9 GeV there exist the peculiar irregularities in various thermodynamic quantities found at chemical freeze-out. The most remarkable irregularity is an unprecedented jump of the number of effective degrees of freedom observed in this narrow energy range which is seen in all realistic versions of the hadron resonance gas model, including the model with the BreitWigner parameterization of the resonance width and the one with a zero width of all resonances. Therefore, the developed concept is called the non-smooth chemical freeze-out. We are arguing that these irregularities evidence for the possible formation of quark gluon bags. In order to develop other possible signals of their formation here we study the apparent width of wide hadronic resonances and quark gluon bags in a thermal environment. Two new effects generated for the wide resonances and quark gluon bags by a thermal medium are discussed here: the near threshold thermal resonance enhancement and the near threshold thermal resonance sharpening. These effects are also analyzed for the Breit-Wigner width parameterization and it is shown that, if the resonance decay thresholds are located far away from the peak of resonance mass attenuation, then such a width parameterization leads to a stronger enhancement of the resonance pressure compared to the Gaussian one. On the basis of the new effects we argue that the most optimistic chance to find experimentally the quark gluon bags may be related to their sharpening and enhancement in a thermal medium. In this case the wide quark gluon bags may appear directly or in decays as narrow resonances that are absent in the tables of elementary particles and that have the apparent width about 50-120 MeV and the mass about or above 2.5 GeV.

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“…Note that a similar equation for pressure (6) was first postulated in Ref. [35] as a generalization of the famous Fisher droplet model [36].…”

Section: Introductionmentioning

confidence: 73%

Alternative formulation of the induced surface and curvature tensions approach

Bugaev

2021

J. Phys. G: Nucl. Part. Phys.

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We develop a novel method to analyze the excluded volume of the multicomponent mixtures of classical hard spheres in the grand canonical ensemble. The method is based on the Laplace-Fourier transform technique and allows one to account for the fluctuations of the particle number density for the induced surface and curvature tensions equation of state. As a result one can go beyond the Van der Waals approximation by obtaining the suppression of the induced surface and curvature tensions coefficients at moderate and high packing fractions. In contrast to the standard induced surface and curvature tensions equation of state the suppression of these coefficients is not an exponential one, but a power-like one. The obtained alternative equation of state is further generalized to account for higher virial coefficients. This result is straightforwardly generalized to the case of quantum statistics.

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Exploring a possible origin of the QCD critical endpoint

Cited by 6 publications

References 30 publications

Hadron resonance gas model with induced surface tension

Hadron resonance gas model with induced surface tension

Non-Smooth Chemical Freeze-Out and Apparent Width of Wide Resonances and Quark Gluon Bags in a Thermal Environment

Alternative formulation of the induced surface and curvature tensions approach

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