2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/199407The critical endpoint (CEP) and the phase structure are studied in the Polyakov-loop extended Nambu--Jona-Lasinio model in which the scalar type eight-quark (σ^4) interaction and the vector type four-quark interaction are newly added. The σ^4 interaction largely shifts the CEP toward higher temperature and lower chemical potential, while the vector type interaction does oppositely. At zero chemical potential, the σ^4 interaction moves the pseudo-critical temperature of the chiral phase transition to the vicinity of that of the deconfinement phase transition.13 pages, 6 figures embedded, accepted for publication in Phys. Lett. BHigh Energy Physics - PhenomenologyNuclear Theorytext