Gamma-ray constraints on decaying dark matter

The anomalies in positron fraction observed in PAMELA and total flux of electrons and positron reported by Fermi can be explained by a decaying dark matter. The agreement between astrophysical background and observed data in anti-proton indicates a lep-tophilic dark matter and constrains the hadronic decay branching ratios. In this work, we study the constrains on decaying rates of a dark matter to various 2-body final states using the Fermi and HESS gamma-ray data. We find that μ⁺μ^- or τ⁺τ^- final state is preferred to simultaneously explain the excesses and meet the gamma-ray constrains.