1204.1971 (Shin Nakamura)

Nonequilibrium Phase Transitions and Nonequilibrium Critical Point from
AdS/CFT    [PDF]

Shin Nakamura

We find novel phase transitions and critical phenomena that occur only outside the linear-response regime of current-driven nonequilibrium states. We consider a (3+1)-dimensional system of strongly-interacting quantum gauge theory defined at the microscopic level. We compute its nonlinear non-ballistic conductivity by using the AdS/CFT correspondence. We find that the system exhibits a nonequilibrium first-order phase transition where the conductivity jumps discontinuously at finite current density. The sign of the differential conductivity also changes there. A nonequilibrium critical point is found at the end point of the first-order regime where critical phenomena are observed. We define nonequilibrium analogues of critical exponents, and their numerical values are obtained. In light of the possible universality, we expect that the newly discovered nonequilibrium critical point can also be found in nature: this provides a prediction of superstring theory for the real world. We also propose a nonequilibrium-steady-state analogue of thermodynamic potential in terms of the gravity-dual theory.

View original: http://arxiv.org/abs/1204.1971