Chiral symmetry and its partial restoration in relativisitic mean field theory for finite nuclei

por Prof. Hiroshi Toki (RCNP Osaka University)

jueves 4 dic. 2003 15:00 → 16:00 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

Chiral symmetry and its spontaneous breaking are important in hadron physics due to the symmetry of the underling QCD theory for the building blocks of hadrons. The chiral sigma model of Gell-Mann and Levy is known to provide good description of the pion nucleon interactions. We take the chiral sigma model for the description of nuclei using the relativistic mean field framework with an extension to include the mass generation term for the omega meson as the nucleon. The direct application of the extended chiral sigma model provides too small spin-orbit splittings, which are essential for the quantitative description of finite nuclei. We introduce then the possibility of surface pion condensation in finite nuclei and find that the mean field of pion becomes finite and provides a suitable amount of additional energy difference between spin-orbit partners.[1,2] The nucleon mass is reduced by about 20%, which corresponds the amount of the chiral symmetry restoration in finite nuclei. 1. H. Toki, S. Sugimoto and K. Ikeda, Prog. Theor. Phys. 108 (2002) 903. 2. Y. Ogawa, H. Toki, S. Tamenaga, H. Shen, A. Hosaka, S. Sugimoto and K. Ikeda, RCNP preprint (2003).