Nuclear matter

About: Nuclear matter is a research topic. Over the lifetime, 10180 publications have been published within this topic receiving 248261 citations.

The Equation of State for the Nucleonic and Hyperonic Core of Neutron Stars

Abstract: We re-examine the equation of state for the nucleonic and hyperonic inner core of neutron stars that satisfies the 2M⊙ observations as well as the recent determinations of stellar radii below 13 km, while fulfilling the saturation properties of nuclear matter and finite nuclei together with the constraints on the high-density nuclear pressure coming from heavy-ion collisions. The recent nucleonic FSU2R and hyperonic FSU2H models are updated in order to improve the behaviour of pure neutron matter at subsaturation densities. The corresponding nuclear matter properties at saturation, the symmetry energy, and its slope turn out to be compatible with recent experimental and theoretical determinations. We obtain the mass, radius, and composition of neutron stars for the two updated models and study the impact on these properties of the uncertainties in the hyperon–nucleon couplings estimated from hypernuclear data. We find that the onset of appearance of each hyperon strongly depends on the hyperon–nuclear uncertainties, whereas the maximum masses for neutron stars differ by at most 0.1M⊙, although a larger deviation should be expected tied to the lack of knowledge of the hyperon potentials at the high densities present in the centre of 2M⊙ stars. For easier use, we provide tables with the results from the FSU2R and FSU2H models for the equation of state and the neutron star mass–radius relation.

High-Density Matter in the Chiral Sigma Model

Abstract: We present a field theoretical equation of state for nuclear matter and neutron-rich matter in β equilibrium using the chiral sigma model. The model includes an isoscalar vector field generated dynamically and reproduces the empirical values of the nuclear matter saturation density and binding energy and the isospin symmetry coefficient for asymmetric nuclear matter. The energy per nucleon of nuclear matter as predicted by our calculation is in very good agreement, up to about a density of 4n s (n s =nucleon number density for saturating nuclear matter), with the estimates inferred from heavy-ion collision data. An astrophysical application, relating to neutron star structure, is presented

Low Density Phases in a Uniformly Charged Liquid

Abstract: This paper is concerned with the macroscopic behavior of global energy minimizers in the three-dimensional sharp interface unscreened Ohta–Kawasaki model of diblock copolymer melts. This model is also referred to as the nuclear liquid drop model in the studies of the structure of highly compressed nuclear matter found in the crust of neutron stars, and, more broadly, is a paradigm for energy-driven pattern forming systems in which spatial order arises as a result of the competition of short-range attractive and long-range repulsive forces. Here we investigate the large volume behavior of minimizers in the low volume fraction regime, in which one expects the formation of a periodic lattice of small droplets of the minority phase in a sea of the majority phase. Under periodic boundary conditions, we prove that the considered energy \({\Gamma}\)-converges to an energy functional of the limit “homogenized” measure associated with the minority phase consisting of a local linear term and a non-local quadratic term mediated by the Coulomb kernel. As a consequence, asymptotically the mass of the minority phase in a minimizer spreads uniformly across the domain. Similarly, the energy spreads uniformly across the domain as well, with the limit energy density minimizing the energy of a single droplet per unit volume. Finally, we prove that in the macroscopic limit the connected components of the minimizers have volumes and diameters that are bounded above and below by universal constants, and that most of them converge to the minimizers of the energy divided by volume for the whole space problem.

Colloidal cluster phases, gelation and nuclear matter

Abstract: The combination of short-range attractions and long-range repulsions can lead to interesting clustering phenomena. In particular there are strong indications that the colloidal cluster phase is in fact a manifestation of such a competition. Here we compute the stability boundary of the cluster phase by invoking counter-ion condensation. It is found that a condensation catastrophe leading to an infinite cluster sets in if the level of charge on the colloid is too low. The same ingredients leading to the cluster phase are found in nuclear physics: strong short-range attractions due to nuclear force and weak long-range Coulomb repulsions. We will show explicitly here the equivalence of a semi-empirical mass formula for the binding energy of the nucleus and the free energy of a cluster in a colloidal cluster phase. This identification enables an exploitation of theoretical results from nuclear physics to the colloidal domain and, perhaps, the construction of a colloidal system mimicking various aspects of nuclear matter.