Dark matter from a complex scalar singlet: the role of dark CP and other discrete symmetries

Abstract

We study the case of a pseudo-scalar dark matter candidate which emerges from a complex scalar singlet, charged under a global U(1) symmetry, which is broken both explicitly and spontaneously. The pseudo-scalar is naturally stabilized by the presence of a remnant discrete symmetry: dark CP. We study and compare the phenomenology of several simplified models with only one explicit symmetry breaking term. We find that several regions of the parameter space are able to reproduce the observed dark matter abundance while respecting direct detection and invisible Higgs decay limits: in the resonances of the two scalars, featuring the known as forbidden or secluded dark matter, and through non-resonant Higgs-mediated annihilations. In some cases, combining different measurements would allow one to distinguish the breaking pattern of the symmetry. Moreover, this setup admits a light DM candidate at the sub-GeV scale. We also discuss the situation where more than one symmetry breaking term is present. In that case, the dark CP symmetry may be spontaneously broken, thus spoiling the stability of the dark matter candidate. Requiring that this does not happen imposes a constraint on the allowed parameter space. Finally, we consider an effective field theory approach valid in the pseudo-Nambu-Goldstone boson limit and when the U(1) breaking scale is much larger than the electroweak scale.

Vector boson dark matter from trinification

“…There are also two T -even singlet scalars at or below the TeV scale, into which this T -odd DM scalar can annihilate. Thus this scenario is very similar to complex singlet DM models where a stable scalar singlet annihilates into its unstable scalar partners [16,17]. If the trinification symmetry breaks down directly to the SM, a combination of scalar singlet, doublet and triplet may be made light to serve the role of DM.…”

“…Unlike the scalar singlet DM model within the context of SM [35,36], here H can annihilate into pairs of h and h, provided that these T -even scalars are lighter than H . This would allow for a significantly larger region of parameter space, analogous to complex singlet DM [16,17].…”

Cancellation mechanism of dark matter direct detection in Higgs-portal and vector-portal models

“…Because of this nice property, many works have followed up the model and studied it in different aspects. For example, many papers have discussed various phenomenologies of the model [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In refs.…”

Vector Boson Dark Matter From Trinification

“…Unlike the scalar singlet DM model within the context of SM [34,35], here H can annihilate into pairs of h and h, provided that these T -even scalars are lighter than H . This would allow for a significantly larger region of parameter space, analogous to complex singlet DM [16,17].…”