Irreversible processes: The generalized affinities within Tsallis statistics

Within the generalized statistical mechanics introduced recently by Tsallis, the generalized form of the affinities (the quantities which drive a process in the theory of irreversible thermodynamics) was derived. The affinities were obtained by considering changes in the generalized entropy SqAUB of a system composed by two subsystems A and B. The non-extensive character of the Tsallis entropy is taken into account. At the end, the equilibrium condition is discussed and the zeroth law in the framework of the generalized thermodynamics is consistently recovered: as in the usual case, two systems which are in equilibrium with a third one are necessarily in equilibrium among them and share the same temperature.