We study soft hadron production in relativistic heavy-ion collisions in a wide range of reaction energy, 4.8 GeV \( \sqrt{{s_{{\rm NN}}}}\)≥200 GeV, we use continuity of particle yields and statistical parameters to predict the hadron production at \( \sqrt{{s_{{\rm NN}}}}\) = 62.4 GeV, and obtain total yields of hadrons at \( \sqrt{{s_{{\rm NN}}}}\) = 130 GeV. We consider, in depth, the pattern we uncover within the hadronization condition, and discuss possible mechanisms associated with the identified rapid change in system properties at \( \sqrt{{s_{{\rm NN}}^{{\rm cr}}}}\) . We propose that the chemically over-saturated 2 + 1 flavor hadron matter system undergoes a 1st-order phase transition.

/pdf/hadron-production-and-phase-changes-in-relativistic-heavy-4rho046tny.pdf

Hadron production and phase changes in relativistic heavy-ion collisions

The purpose of the present article is to call attention to some realistic quasiparticle-based description of the quark/gluon matter and its consistent implementation in thermodynamics. A simple and transparent representation of the thermodynamical consistency conditions is given. This representation allows one to review critically and systemize available phenomenological approaches to the deconfinement problem with respect to their thermodynamical consistency. A particular attention is paid to the development of a method for treating the string screening in the dense matter of unbound color charges. The proposed method yields an integrable effective pair potential which can be incorporated into the mean-field picture. The results of its application are in reasonable agreement with lattice data on the QCD thermodynamics.

https://arxiv.org/pdf/nucl-th/0102027.pdf

Towards thermodynamical consistency of qusiparticle picture

The production of Δ
 0(1232)-resonances in p + 12C collisions at 4.2 GeV/c was investigated with 4π acceptance. The masses and widths of the resonances were obtained from ananalysis of foreground and background invariant-mass distributions of pπ
 − pairs obtained using an angular criterion. The fraction of charged π
 −-mesons coming from the Δ
 0(1232) decay was estimated and compared to those obtained in earlier analyses. The momentum, transverse momentum, kinetic energy, rapidity, and emission angle distributions as well as the invariant cross-sections of Δ
 0(1232)-resonances werere constructed in the laboratory frame. The freeze-out temperature of theΔ
 0(1232)-resonances produced in p + 12C collisions was estimated and compared to the freeze-out temperatures obtained using different methods for Δ(1232)-resonances produced in other experiments with different sets of colliding nuclei at various incident energies.

Production of Δ0(1232)-resonances in p + 12C collisions at a momentum of 4.2 GeV/c

The purpose of the present article is to call attention to some realistic quasiparticle-based description of quark/gluon matter and its consistent implementation in thermodynamics. A simple and transparent representation of the thermodynamic consistency conditions is given. This representation allows one to review critically and systemize available phenomenological approaches to the deconfinement problem with respect to their thermodynamic consistency. Particular attention is paid to the development of a method for treating the string screening in the dense matter of unbound color charges. The proposed method yields an integrable effective pair potential that can be incorporated into the mean-field picture. The results of its application are in reasonable agreement with lattice data on the QCD thermodynamics.

Toward thermodynamic consistency of quasiparticle picture

The production of Δ0(1232)-resonances in p+12C collisions at 4.2 GeV/c was analyzed with 4π acceptance. The mass distribution of Δ0(1232) was reconstructed using an angular criterion. The fraction of charged π−-mesons coming from Δ0(1232) decay was estimated and compared to those obtained in earlier works. The momentum, transverse momentum, kinetic energy, and rapidity distributions as well as invariant cross sections of Δ0(1232)-resonances were reconstructed in the laboratory frame. The mean kinematical characteristics of the reconstructed Δ0(1232) were compared to those of participant protons in experiment and within some of the models. The freeze-out temperature of Δ0(1232) estimated in the present analysis was compared with those obtained using different methods for Δ(1232) produced with other sets of colliding nuclei at various incident energies. The relative number of nucleons excited to Δ0 (1232) at freeze-out conditions in p+12C collisions was estimated.

Analysis of Δ0(1232) production in collisions of protons with carbon nuclei at 4.2 GeV/c

We study the pi+- spectra obtained in 2,4,6,8 A GeV Au-Au collisions within the thermal model. We find that the main features of the data can be well described after we include the pions from the decay of the Delta-resonance with medium mass modification.

Delta-33 medium mass modification and pion spectra

Prolate ellipsoidal bag model for heavy quarkonium

The two phase model for the quark-gluon deconfinement phase transition is modified based on the tempreature and density related properties of the hadron. The revised approach is consistent with the single body description. Its consequences on the pressure and energy density of the hadron gas is investigated, and the critical value of temperature and chemical potential of the phase transition from the hadron gas to a non-interacting quark matter are calculated. Our results agree with the recent lattice gauge calculations.

A revised approach of the two phase model for quark-gluon deconfinement phase transition

The properties of clustered quark matter at finite temperature are studied. It is shown that clustered quark matter can exist only at low temperatures and then it is difficult to detect the new phase by high-energy heavy-ion collisions.

Clustered quark matter at finite temperature.

The prolate ellipsoidal bag model for the {ital Q{bar Q}g} state is discussed in this paper. The dependence of the energy of the system on the interquark separation is obtained. It is found that the energy of the system obtained in this model is much lower than that in a spherical bag model for the same interquark separation. The energy increases with the interquark separation almost linearly in the region of interquark separation from 7 to 20 GeV{sup {minus}1}.

Bi Pin-zhen

Papers

Delta-33 medium mass modification and pion spectra

Prolate ellipsoidal bag model for heavy quarkonium

A revised approach of the two phase model for quark-gluon deconfinement phase transition

Clustered quark matter at finite temperature.

Prolate ellipsoidal bag model for QQ-barg state.