The Semi-Hooperon: Gamma-ray and anti-proton excesses in the Galactic Center

Abstract

A puzzling excess in gamma-rays at GeV energies has been observed in the center of our galaxy using Fermi-LAT data. Its origin is still unknown, but it is well fitted by Weakly Interacting Massive Particles (WIMPs) annihilations into quarks with a cross section around $10^{-26}{\rm cm^3 s^{-1}}$ with masses of $20-50$~GeV, scenario which is promptly revisited. An excess favoring similar WIMP properties has also been seen in anti-protons with AMS-02 data potentially coming from the Galactic Center as well. In this work, we explore the possibility of fitting these excesses in terms of semi-annihilating dark matter, dubbed as semi-Hooperon, with the process ${\rm WIMP\, WIMP \rightarrow WIMP\, X}$ being responsible for the gamma-ray excess, where X=h,Z. An interesting feature of semi-annihilations is the change in the relic density prediction compared to the standard case, and the possibility to alleviate stringent limits stemming from direct detection searches. Moreover, we discuss which models might give rise to a successful semi-Hooperon setup in the context of $\mathcal{Z}_3$,$\mathcal{Z}_4$ and extra "dark" gauge symmetries.