Nuclear matter

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

From Brueckner approach to Skyrme-type energy density functional

Abstract: A Skyrme-like effective interaction is built up from the equation of state of nuclear matter. The latter is calculated in the framework of the Brueckner-Hartree-Fock approximation with two- and three-body forces. A complete Skyrme parametrization requires a fit of the neutron and proton effective masses and the Landau parameters. The new parametrization is probed on the properties of a set of closed-shell and closed-subshell nuclei, including binding energies and charge radii.

Equation of state of nuclear and neutron matter at third-order in perturbation theory from chiral effective field theory

Abstract: We compute from chiral two- and three-nucleon interactions the energy per particle of symmetric nuclear matter and pure neutron matter at third-order in perturbation theory including self-consistent second-order single-particle energies. Particular attention is paid to the third-order particle-hole ring diagram, which is often neglected in microscopic calculations of the equation of state. We provide semianalytic expressions for the direct terms from central and tensor model-type interactions that are useful as theoretical benchmarks. We investigate uncertainties arising from the order-by-order convergence in both many-body perturbation theory and the chiral expansion. Including also variations in the resolution scale at which nuclear forces are resolved, we provide new error bands on the equation of state, the isospin-asymmetry energy, and its slope parameter. We find in particular that the inclusion of third-order diagrams reduces the theoretical uncertainty at low densities, while in general the largest error arises from omitted higher-order terms in the chiral expansion of the nuclear forces.

Gluon production in the Color Glass Condensate model of collisions of ultrarelativistic finite nuclei

Abstract: We extend previous work on high energy nuclear collisions in the Color Glass Condensate model to study collisions of finite ultrarelativistic nuclei. The changes implemented include a) imposition of color neutrality at the nucleon level and b) realistic nuclear matter distributions of finite nuclei. The saturation scale characterizing the fields of color charge is explicitly position dependent, $\Lambda_s=\Lambda_s(x_T)$. We compute gluon distributions both before and after the collisions. The gluon distribution in the nuclear wavefunction before the collision is significantly suppressed below the saturation scale when compared to the simple McLerran-Venugopalan model prediction, while the behavior at large momentum $p_T\gg \Lambda_s$ remains unchanged. We study the centrality dependence of produced gluons and compare it to the centrality dependence of charged hadrons exhibited by the RHIC data. We demonstrate the geometrical scaling property of the initial gluon transverse momentum distributions for different centralities. Classical Yang-Mills results for $p_T \Lambda_s$-the resulting energy per particle is significantly lower than the purely classical estimates. Our results for nuclear collisions can be used as initial conditions for quantitative studies of the further evolution and possible equilibration of hot and dense gluonic matter produced in heavy ion collisions. Finally, we study $pA$ collisions within the classical framework. Our results agree well with previously derived analytical results in the appropriate kinematical regions.

y-scaling analysis of quasielastic electron scattering and nucleon momentum distributions in few-body systems, complex nuclei, and nuclear matter.

Abstract: The approach to y scaling previously adopted to obtain the nucleon momentum distribution in the two- and three-nucleon systems is extended to the case of complex nuclei and nuclear matter. The basic elements of this approach, which takes properly into account nucleon binding and momentum, are reviewed. A new method of analysis, which allows one to obtain the experimental asymptotic scaling function from inclusive cross sections even if these data are affected by final-state interactions, is proposed and illustrated. By such a method, the asymptotic scaling functions of $^{3}\mathrm{He}$, $^{4}\mathrm{He}$, $^{12}\mathrm{C}$, $^{56}\mathrm{Fe}$, and nuclear matter are obtained from recent experimental data and it is demonstrated that, particularly at high negative values of the scaling variable, the available data points at the highest value of the momentum transfer are affected by final-state interaction and cannot therefore be considered to represent the asymptotic scaling function. It is shown that, unlike what is commonly stated, the nucleon momentum distribution is not simply defined in terms of the derivative of the asymptotic scaling function, but as a sum of such a derivative plus the derivative of a quantity, the binding correction, generated by the removal energy distribution of nucleons embedded in the nuclear medium.The binding correction and its derivative are evaluated with various types of spectral functions, and the nucleon momentum distributions in $^{3}\mathrm{He}$, $^{4}\mathrm{He}$, $^{12}\mathrm{C}$, $^{56}\mathrm{Fe}$, and nuclear matter are obtained up to nucleon momenta k\ensuremath{\approxeq}500 MeV/c. For few-body systems the obtained momentum distributions satisfactorily agree with the ones extracted from (e,e'p) reactions and with theoretical calculations performed within Faddeev or variational approaches, whereas for complex nuclei they qualitatively agree with predictions of theoretical many-body approaches which take nucleon-nucleon correlations into account and, at the same time, at k\ensuremath{\ge}350 MeV/c they are larger by orders of magnitude than the ones predicted by mean field approaches. Such a result does represent unambiguous evidence of correlation effects in nuclei.

Nuclear constraints on the moments of inertia of neutron stars

Abstract: The properties and structure of neutron stars are determined by the equation of state (EOS) of neutron-rich stellar matter. While the collective flow and particle production in relativistic heavy-ion collisions have tightly constrained the EOS of symmetric nuclear matter up to about 5 times the normal nuclear matter density, more recent experimental data on isospin diffusion and isoscaling in heavy-ion collisions at intermediate energies have constrained considerably the density dependence of the nuclear symmetry energy at subsaturation densities. Although there are still many uncertainties and challenges to pin down completely the EOS of neutron-rich nuclear matter, heavy-ion reaction experiments in terrestrial laboratories have limited the EOS of neutron-rich nuclear matter to a range much narrower than that spanned by the various EOSs currently used in astrophysical studies in the literature. These nuclear physics constraints could thus provide more reliable information about the properties of neutron stars. Within well-established formalisms using the nuclear-constrained EOSs, we study the moments of inertia of neutron stars. We place special emphasis on component A of the extremely relativistic double neutron star system PSR J0737–3039. Its moment of inertia is found to be between 1.30 × 1045 and 1.63 × 1045 g cm2. Moreover, the transition density at the crust-core boundary is shown to lie in the narrow range ρt = 0.091-0.093 fm−3.