31 research outputs found
Meson-Nucleon Vertex Form Factors at Finite Temperature Using a Soft Pion Form Factor
The temperature and density dependence of the meson-nucleon vertex form
factors is studied in the framework of thermofield dynamics. Results are
obtained for two rather different nucleon-nucleon potentials: the usual Bonn
potential and the variation with a softer form factor, due to Holinde
and Thomas. In general, the results show only a modest degree of sensitivity to
the choice of interaction.Comment: 5 pages, uses revtex
Neutron-Proton Mass Difference in Nuclear Matter and in Finite Nuclei and the Nolen-Schiffer Anomaly
The neutron-proton mass difference in (isospin asymmetric) nuclear matter and
finite nuclei is studied in the framework of a medium-modified Skyrme model.
The proposed effective Lagrangian incorporates both the medium influence of the
surrounding nuclear environment on the single nucleon properties and an
explicit isospin-breaking effect in the mesonic sector. Energy-dependent
charged and neutral pion optical potentials in the s- and p-wave channels are
included as well. The present approach predicts that the neutron-proton mass
difference is mainly dictated by its strong part and that it markedly decreases
in neutron matter. Furthermore, the possible interplay between the effective
nucleon mass in finite nuclei and the Nolen-Schiffer anomaly is discussed. In
particular, we find that a correct description of the properties of mirror
nuclei leads to a stringent restriction of possible modifications of the
nucleon's effective mass in nuclei.Comment: 10 pages, 8 figures, presentation at the 19th Int. IUPAP Conf. on
Few-Body Problems in Physics (Aug.31-Sep.5, 2009, Univ.of Bonn, Germany
Spectra of Quarkonia at Finite Temperature
Finite-temperature spectra of heavy quarkonia are calculated by combining
potential model and thermofield dynamics formalisms. The mass spectra of the
heavy quarkonia with various quark contents are calculated. It is found that
binding mass of the quarkonium decreases as temperature increases.Comment: 12 pages, 1 figure. To appear Mod.Phys.Lett.
Nucleon-nucleon potential in finite nuclei
We consider the spin-isospin-independent central part of the residual
nucleon-nucleon potential in finite spherical nuclei taking into account the
deformation effects of the nucleons within the surrounding nuclear environment.
It is shown that inside the nucleus the short-range repulsive contribution of
the potential is increased and the intermediate attraction is decreased. We
identify the growth of the radial component of the spin-isospin independent
short-range part of the in-medium nucleon-nucleon interaction as the
responsible agent that prevents the radial collapse of the nucleus.Comment: 9 pages, 3 eps figure
Neutron-proton mass difference in nuclear matter
Isospin-breaking effects in nuclear matter are studied in the framework of a
medium-modified Skyrme model. The proposed effective Lagrangian incorporates
both the medium influence of the surrounding nuclear environment on the single
nucleon properties and an explicit isospin-breaking effect in the mesonic
sector. The approach predicts that the neutron-proton mass difference decreases
in isospin-symmetric nuclear matter but by a very small amount only.Comment: 8 pages, 4 figures, revised versio
Neutron-proton mass difference in isospin asymmetric nuclear matter
Isospin-breaking effects in the baryonic sector are studied in the framework
of a medium-modified Skyrme model. The neutron-proton mass difference in
infinite, asymmetric nuclear matter is discussed. In order to describe the
influence of the nuclear environment on the skyrmions, we include
energy-dependent charged and neutral pion optical potentials in the s- and
p-wave channels. The present approach predicts that the neutron-proton mass
difference is mainly dictated by its strong part and that it strongly decreases
in neutron matter.Comment: 11 pages, 6 figures; some new references adde