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We provide conservative bounds on the dark matter cross-section and lifetimefrom final state radiation produced by annihilation or decay into chargedleptons, either directly or via an intermediate particle $\phi$. Our analysisutilizes the experimental gamma-ray flux upper limits from four Milky Way dwarfsatellites: HESS observations of Sagittarius and VERITAS observations of Draco,Ursa Minor, and Willman 1. Using 90% confidence level lower limits on theintegrals over the dark matter distributions, we find that these constraintsare largely unable to rule out dark matter annihilations or decays as anexplanation of the PAMELA and ATIC/PPB-BETS excesses. However, if there is anadditional Sommerfeld enhancement in dwarfs, which have a velocity dispersion~10 to 20 times lower than that of the local Galactic halo, then thecross-sections for dark matter annihilating through $\phi$'s required toexplain the excesses are very close to the cross-section upper bounds fromWillman 1. Dark matter annihilation directly into $\tau$'s is also marginallyruled out by Willman 1 as an explanation of the excesses, and the requiredcross-section is only a factor of a few below the upper bound from Draco.Finally, we make predictions for the gamma-ray flux expected from the dwarfgalaxy Segue 1 for the Fermi Gamma-ray Space Telescope. We find that for asizeable fraction of the parameter space in which dark matter annihilation intocharged leptons explains the PAMELA excess, Fermi has good prospects fordetecting a gamma-ray signal from Segue 1 after one year of observation.

Bounds on Cross-sections and Lifetimes for Dark Matter Annihilation and Decay into Charged Leptons from Gamma-ray Observations of Dwarf Galaxies