Update on scalar singlet dark matter

In view of the measured Higgs mass of 125 GeV, the perturbative renormalization group evolution of the Standard Model suggests that our Higgs vacuum might not be stable. We connect the usual perturbative approach and the functional renormalization group which allows for a straightforward inclusion of higher-dimensional operators in the presence of an ultraviolet cutoff. In the latter framework we study vacuum stability in the presence of higher-dimensional operators. We find that their presence can have a sizable influence on the maximum ultraviolet scale of the Standard Model and the existence of instabilities. Finally, we discuss how such operators can be generated in specific models and study the relation between the instability scale of the potential and the scale of new physics required to avoid instabilities.

Section: A Light Dark Matter Scalarsmentioning

confidence: 72%

Section: A Light Dark Matter Scalarsmentioning

confidence: 99%

The Higgs mass and the scale of new physics

Eichhorn

Gies

Jaeckel

et al. 2015

“…It can also make the electroweak phase transition strongly first order [33,34], and enables us to consider electroweak baryogenesis if there are new sources of CP violation beyond the Kobayashi-Maskawa (KM) phase in the SM with three generations. Finally, if we imposed a new discrete Z 2 symmetry s → −s, the singlet scalar s could make a good dark matter candidate [35][36][37]. This is the standard list for the rationales for considering a singlet scalar s.…”

Section: Modelsmentioning

confidence: 99%

Bounds on Higgs-portal models from the LHC Higgs data

Cheung

Ko²,

Lee

et al. 2015

In a number of Higgs-portal models, an SU(2) isospin-singlet scalar boson generically appears at the electroweak scale and can mix with the Standard Model (SM) Higgs boson with a mixing angle α. This singlet scalar boson can have renormalizable couplings to a pair of dark matter particles, vector-like leptons or quarks, or new gauge bosons, thereby modifying the Higgs signal strengths in a nontrivial way. In this work, we perform global fits to such models using the most updated LHC Higgs-boson data and discuss the corresponding implications on Higgs-portal-type models. In particular we find that the current LHC Higgs-boson data slightly favors the SM over the Higgs-portal singlet-scalar models, which has to be further examined using the upcoming LHC Higgsboson data. Finally, without non-SM particles contributing to the Hγγ and Hgg vertices, the Higgs-portal models are constrained as follows: cos α 0.86 and ∆Γ tot 1.24 MeV at 95% confidence level (CL).

“…Annihilation is p-wave suppressed, as expected for a pair of Majorana DM particles annihilating into scalars. The effective spin-independent (SI) coupling to nucleons is determined by (2.27) and is found to be (using the Higgs-nucleon coupling of [9])…”

Section: Jhep07(2017)047mentioning

confidence: 99%

“…2 Another possibility is to gauge the fermionic field ψ with an abelian group, which gives rise to couplings of the form 9) where A i is the component of the gauge field (technically, averaged along the link between sites i and i + 1 times the lattice spacing a). Under a gauge transformation,…”

Section: Jhep07(2017)047mentioning

confidence: 99%

A clockwork WIMP

Hambye

Teresi

Tytgat

2017

We embed a thermal dark matter (DM) candidate within the clockwork framework. This mechanism allows to stabilize the DM particle over cosmological time because it suppresses its decay into Standard Model (SM) particles. At the same time, pair annihilations are unsuppressed, so that the relic density is set by the usual freeze-out of the DM particle from the thermal bath. The slow decay of the DM candidate is induced by "clockwork" particles that can be quite light (rather than at some GUT or Planck scale) and could be searched for at current or future colliders. According to the scenario considered, the very same particles also mediate the annihilation process, thus providing a connection between DM annihilation and DM decay, and fixing the mass scale of the clockwork states, otherwise unconstrained, to be in the TeV range or lighter. We then show how this setup can minimally emerge from the deconstruction of an extra dimension in flat spacetime. Finally, we argue that the clockwork mechanism that we consider could induce Majorana neutrino masses, with a seesaw scale of order TeV or less and Yukawa couplings of order unity.