Nucleon axial-vector coupling constant in magnetar environments

Abstract

The nucleon axial-vector coupling constant gA is studied in the presence of an external magnetic field, and in dense nuclear environments, to emulate nuclear matter in magnetars. For this purpose we use QCD finite energy sum rules for two-current and three-current correlators, the former involving nucleon-nucleon correlators and the latter involving proton-axial-neutron currents. As a result, the axial-vector coupling constant decreases both with baryon density as well as with magnetic field. The axial-vector coupling evaluated with baryon density near the nuclear density ρ0 leads to gA∗≈0.92. In the presence of magnetic fields gA decreases in general, but gA∗ does not show significant changes.