We study the response of the QCD vacuum to strong magnetic fields, using a potential model for the quark-antiquark interaction. We find that production of spin-polarized $uū$ pairs is energetically favorable for fields $B>\mathrm{}{B}_{\mathrm{crit}}\sim 10\hspace{0.5em}{\mathrm{GeV}}^2.$ We contrast the resulting $uū$ condensate with the quark condensate which is present at zero magnetic field, and we estimate the corresponding magnetization as a function of B.

• Received 30 April 2002

DOI:https://doi.org/10.1103/PhysRevD.66.014004