Current-induced inverse symmetry breaking and asymmetric critical phenomena at current-driven tricritical point

We study critical phenomena associated with a spontaneous chiral symmetry breaking in current-driven non-equilibrium steady states by using holography. We find that the critical exponents $(\gamma, \nu)$ at the tricritical point are asymmetric between the chiral symmetry restored phase and the broken phase. Their values in the broken phase are different from those of the mean-field theory, whereas other critical exponents are the mean-field values. The phase diagram with respect to temperature and current density shows a re-entrant structure: the broken chiral symmetry is restored again at low temperatures in the presence of current density.