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.