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Nuclear Theory·nucl-th

Monday·August 5, 2024

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    New insight into the N/Z and mass equilibration in heavy-ion collisions

    Yu Yang · Zehong Liao · Zepeng Gao · Long Zhu · Jun Su · Cheng Li

    The dynamics of N/Z and mass equilibration are investigated in the reactions 112,124Sn + 239Pu by employing the isospin-dependent quantum molecular dynamics model. It is found that N/Z and mass equilibration take place at different collision stages. The N/Z relaxation is observed in the approaching phase (from first contact to deepest contact) with a very short time, whereas interestingly we find for the first time that mass equilibration only takes place in the separation phase (from the deepest contact to re-separation), which are explained by investigating the dynamical asymmetry between the approaching and separation phases. The mass equilibration also could be clarified with a dynamical potential energy surface. Our results provide a new insight into the equilibration dynamics of the quantum systems.

    nucl-thPRC(2025)·3 citations
  2. 02

    Thermodynamics of the parity-doublet model: Asymmetric and neutron matter

    Jürgen Eser🇩🇪 · Jean-Paul Blaizot🇫🇷

    We consider isospin-asymmetric matter in the parity-doublet model within an extended mean-field calculation, increasing continuously the neutron excess all the way to pure neutron matter. We compute the liquid-gas and the chiral phase transitions occurring at zero to moderate temperatures, but put special emphasis on the phase structure of matter at zero temperature and large baryon densities. The calculation of the free energy involves the solution of gap equations. This is achieved by transforming these gap equations into ordinary differential equations that control the flow with increasing baryon density of various physical quantities: the isoscalar condensate, the densities of protons and neutrons, as well as those of their respective chiral partners. In this formulation, the initial conditions for the differential equations determine the entire phase structure. It is further demonstrated that the threshold for the onset of the population of the chiral partners is exclusively determined by the fermionic parameters, most notably by the chiral-invariant mass of the nucleon. We underline the role of a parity symmetry energy in driving the equilibration of the nucleons and their parity partners across the chiral transition. We provide a detailed analysis of the changes in the matter properties as one varies the neutron excess, including a special discussion of the chiral limit, and we compare systematically the parity-doublet model to its corresponding singlet model, where the chiral partner of the nucleon is neglected. Finally, we focus on neutron matter and compute the equation of state and the speed of sound. The results are confronted to those of other calculations as well as to recent Bayesian analyses of neutron-star observations.

    nucl-thhep-phPRC(2024)·9 citations
  3. 03

    Cluster production and the chemical freeze-out in expanding hot dense matter

    D. Blaschke🇵🇱 · S. Liebing🇩🇪 · G. Röpke🇵🇱 · B. Dönigus🇩🇪

    We discuss medium effects on light cluster production in the QCD phase diagram by relating Mott transition lines to those for chemical freeze-out. In heavy-ion collisions at highest energies provided by the LHC, light cluster abundances should follow the statistical model because of low baryon densities. Chemical freeze-out in this domain is correlated with the QCD crossover transition. At low energies, in the nuclear fragmentation region, where the freeze-out interferes with the liquid-gas phase transition, self-energy and Pauli blocking effects are important. We demonstrate that at intermediate energies the chemical freeze-out line correlates with the maximum mass fraction of nuclear bound states, in particular particles. In this domain, the HADES, FAIR and NICA experiments can give new insights.

    nucl-thhep-phPLB(2025)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE