Two-color QCD in a strong magnetic field: The role of the Polyakov loop

Abstract: We study two-color QCD in an external magnetic backround at finite temperature using the Polyakov-loop extended two-flavor two-color NJL model. At T=0, the chiral condensate is calculated and it is found to increase as a function of the magnetic field $B$. In the chiral limit the deconfinement transition lies below the chiral transition for nonzero magnetic fields $B$. At the physical point, the two transitions seem to coincide for field strengths up to $|qB|\approx 5m_{\pi}^2$ whereafter they split. The splitting between the two increases as a function of $B$ in both the chiral limit and at the physical point. In the range from zero magnetic field and $|qB|=20 m_{\pi}^2$, the transition temperature for the chiral transition increases by approximately 35 MeV, while the transition temperature for deconfinement is essentially constant.