Exploring sub-GeV dark matter via $s$-wave, $p$-wave, and resonance annihilation with CMB data

Yu-Ning Wang, Xin-Chen Duan, Tian-Peng Tang +2

We revisit constraints on sub-GeV dark matter (DM) annihilation via $s$-wave, $p$-wave, and resonance processes using current and future CMB data from Planck, FIRAS, and upcoming e…