2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/184099We investigate the influence of an external magnetic field on chiral symmetry breaking in the Nambu-Jona-Lasinio (NJL) model at finite temperature and chemical potential. According to the Fock-Schwinger proper-time method, we calculate the effective potential in the leading order of the $1/N_c$ expansion. The phase boundary dividing the symmetric phase and the broken phase is illustrated numerically. A complex behavior of the phase boundary is found for large chemical potential.6 pages, 2 figures, Poster talk presented at the Workshop on Finite Density QCD at Nara, Japan, 10-12 July 2003; replaced two referencesHigh Energy Physics - Phenomenologytext