Spontaneous electromagnetic superconductivity of vacuum in strong magnetic field: an evidence from the Nambu--Jona-Lasinio model
Résumé
Using an extended Nambu--Jona-Lasinio model as a low energy effective model of QCD, we support our earlier proposal that the QCD vacuum in a strong external magnetic field (stronger than 10^{16} Tesla) experiences a spontaneous phase transition to an electromagnetically superconducting state. The unexpected superconductivity of, basically, empty space is induced by emergence of quark-antiquark vector condensates with quantum numbers of electrically charged rho mesons. The superconducting phase possesses an anisotropic inhomogeneous structure similar to a periodic Abrikosov lattice in a type-II superconductor. The superconducting vacuum is made of new type of vortices which are topological defects in the charged vector condensates. The superconductivity is realized along the axis of the magnetic field only. We argue that this effect is absent in QED.