Nuclear matter

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

Nuclear thermodynamics from chiral low-momentum interactions

Abstract: We investigate the thermodynamic equation of state of isospin-symmetric nuclear matter with microscopic nuclear forces derived within the framework of chiral effective field theory. Two- and three-body nuclear interactions constructed at low-resolution scales form the basis for a perturbative calculation of the finite-temperature equation of state. The nuclear force models and many-body methods are benchmarked against bulk properties of isospin-symmetric nuclear matter at zero temperature, which are found to be well reproduced when chiral nuclear interactions constructed at the lowest resolution scales are employed. The calculations are then extended to finite temperatures, where we focus on the liquid-gas phase transition and the associated critical point. The Maxwell construction is applied to construct the physical equation of state, and the value of the critical temperature is determined to be ${T}_{c}=17.2$\char21{}19.1 MeV, in good agreement with the value extracted from multifragmentation reactions of heavy ions.

Instabilities of infinite matter with effective Skyrme-type interactions

Abstract: The stability of the equation of state predicted by Skyrme-type interactions is examined. We consider simultaneously symmetric nuclear matter and pure neutron matter. The stability is defined by the inequalities that the Landau parameters must satisfy simultaneously. A systematic study is carried out to define interaction parameter domains where the inequalities are fulfilled. It is found that there is always a critical density ${\ensuremath{\rho}}_{\mathrm{cr}}$ beyond which the system becomes unstable. The results indicate in which parameter regions one can find effective forces to describe correctly finite nuclei and give at the same time a stable equation of state up to densities of 3--4 times the saturation density of symmetric nuclear matter.

Microscopic calculation of the symmetry and Coulomb components of the complex optical-model potential

Abstract: We first investigate how the mass operator for symmetric and uncharged nuclear matter is modified in the presence of a Coulomb field and of neutron excess. Detailed calculations are performed with Reid's hard-core nucleon-nucleon interaction. They are carried out in the framework of the Brueckner-Hartree-Fock approximation, although some higher-order contributions to the low-density expansion of the mass operator are also considered. We relate the mass operator to the optical-model potential. We then use a local density approximation to construct the optical-model potential in a finite nucleus. We find that the half-depth radius of the isoscalar part of the calculated optical-model potential has the form ${r}_{V}{A}^{\frac{1}{3}}$, where $A$ denotes the mass number. Since this property has always been assumed in the phenomenological analysis of the scattering data, a meaningful comparison is possible between our theoretical results for the symmetry and for the Coulomb components of the optical-model potential on the one hand, and the empirical values of these quantities as determined from the analysis of proton and neutron elastic scattering data or of direct charge exchange reactions on the other hand. The calculated depth of the symmetry potential is 11.5 MeV, but its range is larger than that of the isoscalar potential. The calculated value of the so-called Coulomb correction is larger than the one that is assumed in most empirical analyses. The combined effect of these features yields good overall agreement between the calculated and the empirical dependence on neutron excess of the optical-model potential.NUCLEAR REACTIONS Calculation of the symmetry and Coulomb components of the optical-model potential from Reid's hard-core nucleon-nucleon interaction.

Relativistic Heavy‐Ion Physics Without Nuclear Contact

Abstract: An increasing number of physicists are investigating nuclear collisions at relativistic energies. (See figure 1.) Accelerators completely devoted to the study of these collisions (such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory) are under construction. So are hadron colliders (such as the Large Hadron Collider at CERN), which can also be used to accelerate heavy ions. The aim of these projects is to study what happens to nuclear matter at high pressures and temperatures. The expectation is that such experiments will access information that can test important predictions of quantum chromodynamics—for example, a nuclear matter transition from a mixture of quarks and gluons to hadrons, as occurred in the first moments of the universe according to the Big Bang theory.