Quark Momentum Distributions in Relativistic Nuclear Matter

Abstract

We develop the relativistic extension of the study of the (constituent-)quark momentum distribu­ tion in nuclear matter by Arifuzzaman, Hasan and Hoodbhoy. This is performed by employing the relativistic SU(6) model for nucleons and the relativistic Hartree(-Fock) model for nuclear matter. However, the Gaussian function is introduced by hand to describe the quark momentum distribution in a nucleon. Our main interest is in the effect of the relativistic effective mass of nucleons, which is reduced to be smaller than the free value by the mean scalar-meson field, on the quark exchange contribution. We calculate the scalar and vector quark momentum distributions in the interacting relativistic nuclear matter with M*=0.515 M. The differences between the results of the nonrelativistic and relativistic calculations of the total distributions are small. However, as for the quark exchange contributions the differences between them are significant. In other words, the relativistic effect enhances the quark exchange contribution. We therefore· calculate the ratio which is called the EMC ratio. The effect of the relativistic mean-field lowers the value of the nonrelativis­ tic calculation considerably. It is found that the relativistic result agrees with the nonrelativistic one with effectively swollen nucleons.