Almeida-Thouless transition below six dimensions

The existence of an Almeida-Thouless (AT) instability surface below the upper critical six dimensions is demonstrated in the generic replica symmetric field theory. Renormalization flows from around the zero-field fixed point are investigated. By introducing the temperature and magnetic-field dependence of the bare parameters, the fate of the AT line can be followed from mean field (d=infinity) down to d=6-epsilon.