Reopening the Higgs portal for single scalar dark matter

Abstract

A real singlet scalar, connected to the Standard Model sector through a portal with the Higgs boson, is one of the simplest and most popular models for dark matter (DM). However, the experimental advances in direct and indirect DM searches, together with the latest results from the LHC, have ruled out vast areas of the parameter space of this scenario; and are expected to probe it completely within the next years, ruling it out if no signal is found. Motivated by the simplicity of this model, in this article we address a minimal, renormalizable extension that could evade detection, consisting of the addition of an extra real singlet scalar field in the dark sector. We analyze the physical constraints on the model and show that the new annihilation and/or coannihilation channels involving the extra singlet allow to reproduce the correct DM relic abundance while avoiding the bounds from direct and indirect searches for any DM mass above 50 GeV. We also show that, in some interesting regions of the parameter space, the extra particle can be integrated-out, leaving a "clever" effective theory (just involving the DM particle and the Higgs), that essentially reproduces the results.

The waning of the WIMP? A review of models, searches, and constraints

“…A different solution for relaxing DD constraints in the presence of multiple scalar singlets coupled to the SM-Higgs has recently been proposed in Ref. [314].…”

Naturally small Dirac neutrino mass with intermediate SU(2) L multiplet fields

“…Meanwhile, for M φ < M W , the relic density is determined by the Higgs portal. And current direct detection experiments requires that M φ ≈ M h /2 should be satisfied for light DM [92,93]. On the other hand if the dark matter is dominant by η component, either η 0 R or η 0 I , then a mass splitting ∆M = |M η 0 R − M η 0 I | > 100 keV between η 0 R and η 0 I is required to escape the direct detection bound.…”

A Heavy Scalar at the LHC from Vector-Boson Fusion

“…Cuts in (6) and (8) will be applied to the 14 TeV LHC simulations for conservation, the validity of which is guaranteed by the following facts. At first, there is little difference between the 8 TeV LHC and 14 TeV LHC except the collision energy, which means the cut on the pseudorapidity of the first two leading jets should remain unchanged.…”

“…If so, such scalar may leave signatures at dark matter facilities which are in the reach of TeV mass scale. See, e.g., [4][5][6] for very recent studies on this subject.…”