In this paper, we use the mean-field approximation to investigate quark matter described by both SU(2) and SU(3) versions of the Nambu–Jona-Lasinio model at temperatures below 150 MeV and subject to a strong magnetic field. This kind of matter is possibly present in the early stages of heavy-ion collisions and in the interior of protoneutron stars. We have studied symmetric and asymmetric quark matter. The effect of the magnetic field on the effective quark masses and chemical potentials is only felt for quite strong magnetic fields, above $5\times {10}^{18}$ G, with larger effects for the lower densities. Spin polarizations are more sensitive to weaker magnetic fields and are larger for lower temperatures and lower densities. Temperature tends to wash out the magnetic field effects.

• Received 4 March 2011

DOI:https://doi.org/10.1103/PhysRevC.83.065805