University of Hertfordshire

From the same journal

Boosting the dark matter signal with Coulomb resonances

Research output: Contribution to journalArticlepeer-review


  • 1903.00013v2

    Accepted author manuscript, 1.44 MB, PDF document

  • Rakhi Mahbubani
  • Kin Mimouni
View graph of relations
Original languageEnglish
JournalJournal of Cosmology and Astroparticle Physics
Publication statusPublished - 26 Sep 2019


We show that the presence of nearby Coulombic resonances at finite energy could lead to the enhancement of the dark matter annihilation cross section at specific non-zero velocities correlated with the mass splitting between the dark matter pair and that of the resonance. If one of these resonant velocities approximately matches the velocity of dark matter in our local neighbourhood, we would see this enhancement in existing indirect-detection measurements, such as the measurements of the continuum photon spectrum made by HESS and Fermi-LAT. We explore this effect in the context of pure Higgsino and Wino dark matter with a variable splitting between charged and neutral components, controlled by the Wilson coefficient of a higher-dimension operator. For electroweak WIMPs a relevant and appreciable enhancement from Coulomb resonances requires tuning the charged-neutral splitting to be of order the Coulomb binding energies. This leads to strong exclusions of Higgsino dark matter with charged-neutral splittings in the narrow ranges (2, 2.5) and (8.5, 10.5) MeV. In contrast, by decreasing the charged-neutral splitting for the thermal Wino, we can move the Yukawa resonance away from the thermal relic mass, decreasing the indirect-detection signal to a level that is compatible with HESS measurements in the window (25, 35) MeV.


29 pages, 9 figures. v2: published version. Few typos corrected and added comment on perturbative unitarity

ID: 19239212