A new phase for the anisotropic N=4 super Yang-Mills plasma

Black hole solutions of type IIB supergravity have been previously constructed that describe the N=4 supersymmetric Yang-Mills plasma with an anisotropic spatial de- formation. The zero temperature limit of these black holes approach a Lifshitz-like scaling solution in the infrared. We show that these black holes become unstable at low temper- ature and we construct a new class of black hole solutions which are thermodynamically preferred. The phase transition is third order and incorporates a spontaneous breaking of the SO(6) global symmetry down to SO(4)� SO(2). The critical exponents for the phase transition are given by (�;�;;�) = ( 1; 1; 1; 2) which dier from the standard mean-�eld exponents usually seen in holography. At low temperatures the black holes approach a novel kind of scaling behaviour in the far IR with spatial anisotropy and hyperscaling vio- lation. We show that the new ground states are thermal insulators in the direction of the anisotropy.