title: Effective nucleon masses in symmetric and asymmetric nuclear matter.
abstract: The momentum and isospin dependence of the in-medium nucleon mass are studied. Two definitions of the effective mass, i.e., the Dirac mass m*D and the nonrelativistic mass m*NR which parametrizes the energy spectrum, are compared. Both masses are determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a distinct peak around the Fermi momentum. The proton-neutron mass splitting in isospin asymmetric matter is m*D,n<m*D,p and opposite for the nonrelativistic mass, i.e., m*NR,n>m*NR,p, which is consistent with nonrelativistic approaches.
authors.affiliation: Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany.
authors.forename: E N E
authors.initials: EN
authors.lastname: van Dalen
authors.forename: C
authors.initials: C
authors.lastname: Fuchs
authors.forename: Amand
authors.initials: A
authors.lastname: Faessler