Influence of a repulsive vector coupling in magnetized quark matter

Abstract

We consider two flavor magnetized quark matter in the presence of a repulsive vector coupling ($G_V$) devoting special attention to the low temperature region of the phase diagram to show how this type of interaction counterbalances the effects produced by a strong magnetic field. The most important effects occur at intermediate and low temperatures affecting the location of the critical end point as well as the region of first order chiral transitions. When $G_V=0$ the presence of high magnetic fields ($eB \ge 10 m_\pi^2$) increases the density coexistence region with respect to the case when $B$ and $G_V$ are absent while a decrease of this region is observed at high $G_V$ values and vanishing magnetic fields. Another interesting aspect observed at the low temperature region is that the usual decrease of the coexistence chemical value (Inverse Magnetic Catalysis) at $G_V=0$ is highly affected by the presence of the vector interaction which acts in the opposite way. Our investigation also shows that the presence of a repulsive vector interaction enhances the de Haas-van Alphen oscillations which, for very low temperatures, take place at $eB \lesssim 6 m_\pi^2$. We observe that the presence of a magnetic field, together with a repulsive vector interaction, gives rise to a complex transition pattern since $B$ favors the appearance of multiple solutions to the gap equation whereas $G_V$ turns some metastable solutions into stable ones allowing for a cascade of transitions to occur.