Mutual thermal equilibrium in long-range Ising model using nonadditive   entropy
  Mutual equilibrium in long-range interacting systems which involve nonadditive energy, is effectively described in terms of entropy with a nonadditive composition rule. As an example, long range Ising model is considered. The generality of the term having product of the system entropies is pointed out in this framework. 
Ramandeep S. Johal