Large Nc Deconfinement Transition in the Presence of a Magnetic Field

We investigate the effect of a homogeneous magnetic field on the thermal deconfinement transition of QCD in the large $N_c$ limit. First we discuss how the critical temperature decreases due to the inclusion of $N_f\ll N_c$ flavors of massless quarks. Then we study the equivalent correction in the presence of an external Abelian magnetic field. To leading order in $N_f\mathrm{/}{N}_c$, the fact that the deconfinement critical temperature decreases with the magnetic field depends solely on quarks behaving paramagnetically. Finally, we discuss the effects from a finite quark mass and its competition with magnetic effects.