title: Dark matter with pseudoscalar-mediated interactions explains the DAMA signal and the galactic center excess.
abstract: We study a Dirac dark matter particle interacting with ordinary matter via the exchange of a light pseudoscalar, and analyze its impact on both direct and indirect detection experiments. We show that this candidate can accommodate the long-standing DAMA modulated signal and yet be compatible with all exclusion limits at 99(S)% C.L. This result holds for natural choices of the pseudoscalar-quark couplings (e.g., flavor universal), which give rise to a significant enhancement of the dark matter-proton coupling with respect to the coupling to neutrons. We also find that this candidate can accommodate the observed 1-3 GeV gamma-ray excess at the Galactic center and at the same time have the correct relic density today. The model could be tested with measurements of rare meson decays, flavor changing processes, and searches for axionlike particles with mass in the MeV range.
authors.affiliation: GRAPPA Institute, University of Amsterdam, Science Park 904, 1090 GL Amsterdam, Netherlands and Institut d'Astrophysique de Paris, 98 Bis Boulevard Arago, 75014 Paris, France.
authors.forename: Chiara
authors.initials: C
authors.lastname: Arina
authors.affiliation: Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, California 90095, USA.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Del Nobile
authors.affiliation: Institut d'Astrophysique de Paris, 98 Bis Boulevard Arago, 75014 Paris, France.
authors.forename: Paolo
authors.initials: P
authors.lastname: Panci