Relativistic Study of Medium Polarization Effects on Superfluidity in Nuclear Matter

Pairing correlation in nuclear matter has long been studied mainly in neutron matter from a view point of neutron-star physics such as cooling rates . In addition, pairing in nuclear matter with finite Z/N ratio is also becoming of interest as a basic information for the structure theory of finite nuclei, since recent development of RI-beam experiments makes it possible to study N ≃ Z medium-heavy nuclei and neutron-rich light nuclei. At present, there are two ways to describe the fundamental properties such as the saturation property of the finite-density nuclear many-body system; the non-relativistic and the relativistic models. They are understood as describing observed properties almost equally. Among them, we here adopt the latter because of its relative proximity to the underlying field theory. The origin of quantum hadrodynamics (QHD) can be traced back to Duerr’s relativistic nuclear model 2 which reformulated a non-relativistic field theoretical model of Johnson and Teller . Since Chin and Walecka succeeded in reproducing the saturation property of symmetric nuclear matter within the mean-field approximation , QHD has not only been evolving beyond the mean-field approximation as a many-body theory but also been enlarging its objects as a nuclear structure model as infinite matter → spherical → deformed → rotating