A closer look at CP-violating Higgs portal dark matter as a candidate for the GCE

Abstract

A statistically significant excess of gamma rays has been reported and robustly confirmed in the Galactic Center over the past decade. Large local dark matter densities suggest that this Galactic Center Excess (GCE) may be attributable to new physics, and indeed it has been shown that this signal is well-modelled by annihilations dominantly into $$ b\overline{b} $$ b b ¯ with a WIMP-scale cross section. In this paper, we consider Majorana dark matter annihilating through a Higgs portal as a candidate source for this signal, where a large CP-violation in the Higgs coupling may serve to severely suppress scattering rates. In particular, we explore the phenomenology of two UV completions, a singlet-doublet model and a doublet-triplet model, and map out the available parameter space which can give a viable signal while respecting current experimental constraints.

Bound states of WIMP dark matter in Higgs-portal models. Part II. Thermal decoupling

“…The model of eq. (2.1) and various aspects of its phenomenology have been considered for general parameters extensively in the past [17][18][19][20][21][22][23][24][25][26]. Here we will only briefly review the mass eigenstates and their interactions after electroweak symmetry breaking for the choice of parameters denoted in eqs.…”

“…δL ⊃ χ n Hχ n+1 + h.c., where χ n stands for a fermionic or bosonic n-plet under SU L (2), and DM is the lightest neutral mass eigenstate arising from the mixing of χ n and χ n+1 after the electroweak phase transition (EWPT). These models have been among the archetypical scenarios of DM coupled to the Weak interactions of the SM (WIMPs) [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

Snowmass2021 Cosmic Frontier White Paper: Puzzling Excesses in Dark Matter Searches and How to Resolve Them

“…If the GCE is interpreted as a dark matter annihilation signal, then the observed excess is well-modelled by processes which produce b b or µ + µ − final states [91]. Compelling explanations, which are both minimal and viable, can be found in thermal relic dark matter models with a Higgs portal coupling [92,93]. Some such models can be probed at direct detection or collider experiments, settling complementary constraints on the possibilities.…”

Bound states of WIMP dark matter in Higgs-portal models. Part I. Cross-sections and transition rates

“…Various aspects of its phenomenology and experimental constraints of the model (2.1) have been considered extensively in the past [29][30][31][32][33][34][35][36][37][38], and we shall not review them here. We only note that after the EWPT, S and D mix to produce three neutral mass eigenstates, the lightest of which is stable and can play the role of DM.…”

“…Such scenarios have been considered extensively in the literature, and appear also in supersymmetry, e.g. Bino-Higgsino or Higgsino-Wino DM [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. For concreteness, we shall focus on the most minimal such model with a Majorana singlet and a Dirac doublet [29][30][31][32][33][34][35][36][37][38][39].…”