Title: Aspects of Sommerfeld Enhancement in the light of Halo gamma-ray excess
Abstract: We examine Sommerfeld enhancement in dark matter annihilation as a potential origin of the halo-like gamma-ray excess near E ~ 20 GeV reported by Totani. A minimal model with a light CP-even scalar mediator naturally produces a velocity-dependent annihilation cross section consistent with thermal freeze-out, the Milky Way excess, and limits from dwarf spheroidal galaxies. We discuss future prospects and potentially relevant topics including other gamma-ray excess around Galactic Center, and other cosmic ray signals and constraints.