Strong magnetic field corrections to the NJL coupling constant from vacuum polarization

• Autor(a) principal: Moreira, Thiago Henrique
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/11878
• topic: Nambu-Jona-Lasinio; Magnetic field; Magnetic catalysis; Magnetic field dependent coupling; Campo magnético; Catálise magnética; Acoplamento dependente do campo magnético; CIENCIAS EXATAS E DA TERRA::FISICA::FISICA GERAL

In this work we calculate corrections to the NJL model coupling constant in the presence of a uniform magnetic field. Starting with the Nambu-Jona-Lasinio Lagrangian coupled with an external magnetic field, we separate the quark field into two components: one corresponding to the condensed quarks and the other corresponding to the interacting quasiparticle quarks. By integrating out the former, an effective action in terms of the interacting quarks is obtained. We then expand the quark determinant in terms of the quark currents and show that the first-order term provides a correction to the quark masses given by the gap equation. The values obtained for the constituent quark masses increase with the magnetic field, which signals the enhancement of chiral symmetry breaking by the external field and therefore showing that the system exhibits magnetic catalysis. The second-order term of the quark determinant expansion provides a correction to the NJL coupling constant, which decreases with increasing magnetic field for the scalar interactions and increases with increasing magnetic field for the pseudoscalar ones. We then consider a NJL model with the flavor- and B-dependent couplings obtained from vacuum polarization and compute quark and meson masses. While the scalar couplings seem to improve the conciliation with lattice results for the quark masses, the same cannot be said about the pseudoscalar couplings which alters the pseudoscalar meson masses in a different way than what is known in the literature due to its behavior with the applied field.