2025/05/07 by Krnjaic, Gordan · 7 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2505.04626
In light of recent DAMIC-M results, we present the status of thermal-relic dark matter χ coupled to a kinetically-mixed dark photon A^′. In the predictive "direct annihilation" regime, mA' > mχ, the relic abundance depends on the kinetic mixing parameter, and there is a minimum value compatible with thermal freeze out. Using only electron and nuclear recoil direct detection results, we find that for complex scalar dark matter, the direct-annihilation regime is now excluded for nearly all values of mχ; the only exception is the resonant annihilation regime where mA'≈ 2 mχ. Direct annihilation relic targets for other representative models, including Majorana and Pseudo-Dirac candidates, remain viable across a wide range of model parameters, but will be tested with a combination of dedicated accelerator searches in the near future. In the opposite "secluded annihilation" regime, where mχ> mA', this scenario is excluded by cosmic microwave background measurements for all mχ\lesssim 30 GeV. Similar conclusions in both the direct and secluded regimes hold for all anomaly-free vector mediators that couple to the first generation of electrically-charged Standard Model particles.