[en] Explosive astrophysical systems - such as supernovae or compact star binary mergers - provide conditions where exotic degrees of freedom can be populated. Within the covariant density functional theory of nuclear matter we build several general purpose equations of state which, in addition to the baryonic octet, account for Δ(1232) resonance states. The thermodynamic stability of Δ-admixed nuclear matter is investigated in the limiting case of vanishing temperature for charge fractions Y${}_Q$=0.01 and Y${}_Q$=0.5 and wide ranges of the coupling constants to the scalar and vector mesonic fields. General purpose equation of state models with exotica presently available on the CompOSE database are further reviewed; for a selection of them we then investigate thermal properties for thermodynamic conditions relevant for core-collapse supernovae and binary neutron star mergers. Modifications induced by hyperons, Δ(1232), K${}^{-<!--\; ???\; -->}$, pions and quarks are discussed.

[en] Within the covariant density functional theory of nuclear matter we build equations of state of Δ-admixed compact stars. Uncertainties in the interaction of $\mathrm{\Delta }(1232)$ resonance states with nuclear matter, due to lack of experimental data, are accounted for by varying the coupling constants to scalar and vector mesonic fields. We find that, over a wide range of the parameter space allowed by nuclear physics experiments and astrophysical observations, cold catalyzed star matter exhibits a first order phase transition which persists also at finite temperature and out of β-equilibrium in the neutrino-transparent matter. Compact stars featuring such a phase transition in the outer core have small radii and, implicitly, tidal deformabilities. The parameter space is identified where simultaneously Δ-admixed compact stars obey the astrophysical constraint on maximum mass and allow for dUrca processes, which is otherwise forbidden.

[en] Nuclear (multi-)fragmentation, defined as the nuclear decay mechanism in which at least three intermediate mass fragments (Z ≥ 3) are produced, is the disassembly phenomenon specific to hot nuclear matter produced in nuclear collisions at beam energies of 20–100 MeV/nucleon. Considered as the manifestation of the liquid-gas phase transition predicted by nuclear matter mean-field models or an instrument to address the nuclear equation of state, it enjoys for thirty years a vivid scientific interest and motivates the construction of more and more high-performance 4π-detectors allowing for almost complete reaction characterisation on an event-by-event basis. Over the years, many experimental signatures of first- and second-order phase transitions have been proposed and identified in both central and peripheral collisions. Despite their seemingly puzzling messages, coherent understanding of multifragmentation is possible accounting for statistical ensemble inequivalence and finite size effects. Two particular situations will be discussed in detail. The first one corresponds to a multifragmenting medium size nucleus where the expected first-order phase transition is blurred by surface effects. The second one corresponds to an infinitely large system, the clusterized nuclear matter thought to constitute the main sector of baryonic matter in (proto-)neutron stars, where the first-order phase transition is quenched by Coulomb effects. In both cases statistical models with cluster degrees of freedom have been employed.

[en] The microcanonical multifragmentation model developed by us is used to investigate finite size effects on nuclear multifragmentation. A critical-like behavior is observed in all considered cases, in both primary and asymptotic stages of the decay, when the long range Coulomb interaction is present or when it is switched off. Taking into account that the quality of the scaling is improving when the freeze-out volume is decreasing, one may conclude that the apparent scaling is a spreading effect of the thermodynamical critical point due to finite size. It is also observed that the isotopic scaling usually used as a prove of statistical equilibration of nuclear sources is affected by the finite size effects of the source. An one component Lennard-Jones fluid is used to investigate the homogeneity and finite size effects on the phase diagram. The result is that not even a 1000 particle system can be used to describe the thermodynamics of infinite matter. (authors)

[en] We review the equation of state (EoS) models covering a large range of temperatures, baryon number densities and electron fractions presently available on the CompOSE database. These models are intended to be directly usable within numerical simulations of core-collapse supernovae, binary neutron star mergers and proto-neutron star evolution. We discuss their compliance with existing constraints from astrophysical observations and nuclear data. For a selection of purely nucleonic models in reasonable agreement with the above constraints, after discussing the properties of cold matter, we review thermal properties for thermodynamic conditions relevant for core-collapse supernovae and binary neutron star mergers. We find that the latter are strongly influenced by the density dependence of the nucleon effective mass. The selected bunch of models is used to investigate the EoS dependence of hot star properties, where entropy per baryon and electron fraction profiles are inspired from proto-neutron star evolution. The $\mathrm{\Gamma <!--\; ??\; -->}$-law analytical thermal EoS used in many simulations is found not to describe well these thermal properties of the EoS. However, it may offer a fair description of the structure of hot stars whenever thermal effects on the baryonic part are small, as shown here for proto-neutron stars starting from several seconds after bounce.

[en] The annual report of the Horia Hulubei National Institute for Physics and Nuclear Engineering, IFIN-HH, on 2000 presents progress reports in the fields of Theoretical Physics (Nuclear and Atomic Physics (1 paper), Mathematical Physics, Field Theory and Elementary Particles (4 papers), Physics of Information (11 papers)), Nuclear Physics (Nuclear Structure (12 papers), Nuclear Reactions (11 papers), Applied Nuclear Physics (6 papers)), Atomic Physics (1 paper), Cosmic Rays and Nuclear Astrophysics (3 papers), Inertial Fusion, Physics of Neutrons and Nuclear Transmutations (3 papers), Nuclear Instruments and Methods (12 papers), Particle Physics (11 papers), Health and Environmental Physics (8 papers), Applied Physics (13 papers), Tracers, Radiopharmaceuticals and Radiometry (8 papers), Waste management and Site Restoration (1 paper) and Standardization (2 papers). Appendices are added listing the publications in journals, monographs and as preprints, contributions to international conferences, PhD theses, and scientific exchanges (foreign visitors, invited seminars, visits abroad, seminars abroad). Finally the Institute scientific board and research staff are listed

[en] The annual report of the Horia Hulubei National Institute for Physics and Nuclear Engineering, IFIN-HH, on 1999 presents progress reports in the fields of Theoretical Physics (Nuclear and Atomic Physics (14 papers); Mathematical Physics, Field Theory and Elementary Particles (5 ); Physics of Information (6)), Nuclear Physics (Nuclear Structure (11), Nuclear Reactions (10), Atomic Physics (3), Cosmic Rays and Nuclear Astrophysics (3), Physics of Neutrons (2); Nuclear Instruments and Methods (11)), Particle Physics (7), Health and Environmental Physics (10), Applied Physics (21), Tracers, Radiopharmaceuticals and Radiometry (16), Technological Development (2), Waste management and Site Restoration (2) and Standardization (4). Appendices are added listing the publications in journals, monographs and as preprints, contributions to international conferences, PhD theses, and scientific exchanges (foreign visitors, invited seminars, visits abroad, seminars abroad). Finally the Institute scientific board and research staff are listed

[en] The annual report on 1998 of the Horia Hulubei National Institute for Physics and Nuclear Engineering, presents the Institute's activity in the fields of Theoretical Physics (Nuclear and Atomic Physics, Mathematical Physics, Field Theory, and Particle Physics, and Physics of Information), Experimental Physics (Nuclear Structure, Nuclear Reactions, Atomic Physics, Particle Physics, Cosmic Rays and Nuclear Astrophysics, Inertial Physics, Neutron Physics, and Nuclear Transmutations and Nuclear Instruments and Methods), Biophysics, Applied Physics, Radiation Processing, Tracers and Radiometry, Technological Development, Waste Management and Site Restoration, Standardization. Also, data concerning the Publications, Conferences, Patents, PhD Theses, Scientific Exchanges, Visitors, Invited Seminars, Visits and Seminars abroad are given in appendices. The Report gives also the Directorate, the Heads of Departments and the Research Staff

[en] The properties of compact stars and their formation processes depend on many physical ingredients. The composition and the thermodynamics of the involved matter is one of them. We will investigate here uniform strongly interacting matter at densities and temperatures, where potentially other components than free nucleons appear such as hyperons, mesons or even quarks. In this paper we will put the emphasis on two aspects of stellar matter with non-nucleonic degrees of freedom. First, we will study the phase diagram of baryonic matter with strangeness, showing that the onset of hyperons, as that of quark matter, could be related to a very rich phase structure with a large density domain covered by phase coexistence. Second, we will investigate thermal effects on the equation of state (EoS), showing that they favor the appearance of non-nucleonic particles. We will finish by reviewing some recent results on the impact of non-nucleonic degrees freedom in compact star mergers and core-collapse events, where thermal effects cannot be neglected. (orig.)