Light thermal dark matter beyond p-wave annihilation in minimal Higgs portal model
Yutong Chen, Shigeki Matsumoto, Tian-Peng Tang, Yue-Lin Sming Tsai, Lei Wu
Abstract
A bstract This study explores a minimal renormalizable dark matter (DM) model, incorporating a sub-GeV Majorana DM and a singlet scalar particle ϕ . Using scalar and pseudo-scalar interactions (couplings c s and c p ), we investigate implications for DM detection, considering s -wave, p -wave, and combined ( s + p wave) contributions in DM annihilation cross-section, as well as loop-correction contributions to DM-nucleon elastic scattering. Identifying a broad parameter space (10 MeV < m χ ≲ m ϕ ) within the 2 σ allowed region, we explore scenarios (| c s | ≫ | c p |, | c s | ≪ | c p |, and | c s | ≈ | c p |). We find that (i) a non-zero pseudo-scalar coupling alleviates direct detection constraints as a comparison with the previous pure scalar coupling case; (ii) CMB observations set stringent limits on pseudo-scalar interaction dominant cases, making s -wave annihilation viable only for m χ > 1 GeV; (iii) the preferred ϕ -resonance region can be tested in the future indirect detection experiments, such as e-ASTROGAM.