  We explore chiral symmetry breaking in a magnetic field within a
Nambu-Jona-Lasinio model of interacting massless quarks including tensor
channels. We show that the new interaction channels open up via Fierz
identities due to the explicit breaking of the rotational symmetry by the
magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry
breaking leads to the generation of two independent condensates, the
conventional chiral condensate and a spin-one condensate. While the chiral
condensate generates a dynamical fermion mass, the new condensate gives rise to
a dynamical anomalous magnetic moment for the fermions. As a consequence, the
spectrum of the excitations in all Landau levels, except the lowest one,
exhibits Zeeman splitting. Since the pair, formed by a quark and an antiquark
with opposite spins, possesses a resultant magnetic moment, an external
magnetic field can align it giving rise to a net magnetic moment for the ground
state. This is the physical interpretation of the spin-one condensate. Our
results show that the magnetically catalyzed ground state in QCD is actually
richer than previously thought. The two condensates contribute to the effective
mass of the LLL quasiparticles in such a way that the critical temperature for
chiral symmetry restoration becomes enhanced.
