Comment on "Dark Matter with Pseudoscalar-Mediated Interactions Explains the DAMA Signal and the Galactic Center Excess"

TL;DR

This paper critiques a dark matter model explaining the Galactic Center excess and DAMA signal, showing that proper interaction modeling excludes the parameter overlap previously claimed, especially for certain mediator masses.

Contribution

It demonstrates that using the full interaction form, rather than contact approximation, rules out the previously suggested parameter overlap between gamma-ray excess and DAMA signals.

Findings

Gamma-ray excess parameters are outside DAMA's 3σ region for heavy-flavor-universal couplings.

Overlap occurs only for Higgs-like couplings with mediator mass below 15 MeV.

Long-range interactions dominate at DAMA for light mediators.

Abstract

Arina et al. have proposed the Dirac fermionic dark matter with pseudoscalar-mediated interactions to explain the Galactic Center excess, correct relic density and DAMA signal. They have assumed that contact interactions remain roughly valid in calculating scattering rates at the direct detection even when the mediator mass is the same order as the typical momentum transfer. We show that such a replacement is not suitable. Adopting the full form of interactions, we show that the gamma-ray excess allowed parameters are completely outside of the DAMA iodine 3$\sigma$ region, even for heavy-flavor-universal couplings, for which $m_{DM} \sim 40$ GeV in the gamma-ray excess fit. As for Higgs-like couplings, the two regions overlap for $m_a\lesssim$ 15 MeV, where long-range interactions, instead of contact interactions, occur at the DAMA.