Chemical and mechanical instabilities in high energy heavy-ion collisions

[摘要] We investigate the possible thermodynamic instability in a warm and dense nuclear medium where a phase transition from nucleonic matter to resonance-dominated Δ-matter can take place. Such a phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the isospin concentration) in asymmetric nuclear matter. Similarly to the liquid-gas phase transition, the nucleonic and the Δ-matter phase have a different isospin density in the mixed phase. In the liquid-gas phase transition, the process of producing a larger neutron excess in the gas phase is referred to as isospin fractionation. A similar effects can occur in the nucleon-Δ matter phase transition due essentially to a Δ-excess in the Δ-matter phase in asymmetric nuclear matter. In this context, we study the hadronic equation of state by means of an effective quantum relativistic mean field model with the inclusion of the full octet of baryons, the Δ-isobar degrees of freedom, and the lightest pseudoscalar and vector mesons. Finally, we will investigate the presence of thermodynamic instabilities in a hot and dense nuclear medium where phases with different values of antibaryon-baryon ratios and strangeness content may coexist. Such a physical regime could be in principle investigated in the future high-energy compressed nuclear matter experiments where will make it possible to create compressed baryonic matter with a high net baryon density.

[发布机构] Dipartimento di Fisica, Università di Torino, Torino; I-10126, Italy^1;Department of Applied Science and Technology, Politecnico di Torino, Torino; I-10129, Italy^2;INFN, Sezione di Torino, Torino; I-10125, Italy^3

[效力级别] 力学 [学科分类] 力学，机械学

[关键词] Asymmetric nuclear matter;Compressed baryonic matters;Equation of state;High energy heavy-ion collision;Liquid-gas phase transition;Mechanical instabilities;Relativistic mean fields;Thermodynamic instability