Decaying Dark Matter Baryons in a Composite Messenger Model
  A baryonic bound state with a mass of O(100) TeV, which is composed of strongly interacting messenger quarks in the low scale gauge mediation, can naturally be the cold dark matter. Interestingly, we find that such a baryonic dark matter is generically metastable, and the decay of this dark matter can naturally explain the anomalous positron flux recently observed by the PAMELA collaboration. 
Koichi Hamaguchi, Eita Nakamura, Satoshi Shirai and T. T. Yanagida