S-matrix approach to equation of state of nuclear matter

Abstract

We calculate the equation of state of nuclear matter based on the general analysis of the grand canonical partition function in the $S$-matrix framework. In addition to the low mass stable particles and their two-body scattering channels considered earlier, the calculation includes systematically all the higher mass particles and their exited states as well as the scattering channels formed by any number of these species. We estimate the latter contribution by resonances in all the channels. The resulting model-independent virial series for pressure gets substantial contribution from the heavy particles and the channels containing them. The series converges for larger values of baryon density than found earlier.Comment: Version to appear in PRC, Rapid Communication

Symmetry coefficients and incompressibility of clusterized supernova matter

“…Using the virial expansion technique, Horowitz and Schwenk [32] have evaluated the symmetry energy coefficients of clusterized dilute nuclear matter where the cluster species were neutrons, protons, and α particles. In the S-matrix approach, the calculations in nuclear matter were extended with inclusion of all possible heavier clusters [30]. The so-calculated results were found to be appreciably different from those obtained in Ref.…”

“…These results are model dependent, which seems unavoidable at near-normal densities and above. At lower densities, however, based on the general analysis of the grand-canonical partition function for nuclear matter in the S-matrix framework [30,31], it is possible to have predictions for various nuclear observables which are practically model independent. For dilute nuclear matter, the system minimizes its total free energy by forming clusters.…”

Pion structure in the nuclear medium

“…Other studies dealt with the pion decay constant in a composite-operator approach [14], pion cloud effects on the Drell-Yan scattering [15], mass shifts via in-medium chiral perturbation theory [16][17][18], masses and decay constants within a Dyson-Schwinger and Bethe-Salpeter equation ansatz [19]. Furthermore, the pion in finite density has been studied with QCD sum-rule approaches [20], using virial expansions [21], a non-local chiral quark model [22], a relativistic mean field approach [23], and by exploiting operator relations in QCD [24].…”

Temperature dependence of the symmetry energy of finite nuclei

“…The temperature dependence becomes more prominent at low densities, particularly for F s . In stellar core-collapse or bounce phase, matter is, however, not homogeneous, it is nucleated [7,8] and therefore it is important to know how the symmetry energies of finite nuclei behave with increasing temperature. The present communication is aimed to understand this feature.…”