Pairing correlation in nuclear matter from Skyrme force

The properties of pairing correlation in nuclear matter are investigated by using various versions of Skyrme forces. Truncation of states involving pairing correlation, necessary due to zero range nature of the Skyrme force, is discussed in detail. A plateau appears in pairing gap versus cutoff for each force. We propose to choose the cutoff parameter in the middle of the plateau so that the parameterization is independent of nuclides. The mean field theory with the Skyrme force [1, 2] has been successful in describing properties of the atomic nucleus. Bulk features such as binding energies and radii have been reproduced well and, in addition, more detailed properties such as fission barriers, giant resonances, single-particle spectra and low-lying coherent particle-hole and particle-particle excitations have been studied. Various versions of the force have been constructed for specific purposes. Dobaczewski et al. [3] proposed the SkP force in order to describe the pairing properties. While pairing correlation contributes to various properties of nuclei, one of the most interesting topics is the formation of skins and halos in neutron excess nuclei. In these nuclei the neutron Fermi energy rises close to but below zero so that unoccupied neutron orbitals just above the Fermi level are unbound. Therefore the pairing interaction scatters particle pairs from bound states to continuum states. This process can have sizable amplitude in the peripheral region and the formation of neutron skin or halo can be enhanced. Pairing correlation in neutron excess nuclei is also discussed in other articles, e.g. ref. [4].