Effects of isospin-asymmetric media on pionic modes
Departamento de Física da Universidade de Coimbra - P3000 Coimbra, Portugal
Accepted: 13 February 1997
Collective excitations with pion quantum numbers are investigated in media with isospin asymmetry, within the framework of a Nambu-Jona-Lasinio–type model. Two main effects are shown to occur: the splitting between the two charged isospin multiplets and the appearance, at a low threshold density, of a third low-lying charged mode, situated below the lower boundary of the Fermi sea particle-hole excitation continuum. It is also shown that the contribution of this mode for the satisfaction of the generalized GMOR relation becomes dominant in a certain range of densities.
PACS: 11.30.Rd – Chiral symmetries / 12.39.Ki – Relativistic quark model
© EDP Sciences, 1997