Minimal renormalizable simplified dark matter model with a pseudoscalar mediator

Abstract

We consider a minimal renormalizable and gauge invariant dark matter (DM) model, in which the singlet fermion DM has only axial couplings to a new pseudoscalar mediator. The mixing between the pseudoscalar mediator and the standard model (SM) Higgs boson induces the interactions between the DM and SM particles. The DM candidate in this model can provide the correct thermal relic density and evades all direct detections, while it can produce observable signals in indirect detection experiments due to its large annihilation cross section. A comparative study for DM phenomenology at the LHC is conducted for models with scalar mediators that have either scalar or pseudoscalar couplings to SM particles and the DM. We find that the three scenarios have distinguishable features in scalar decay branching ratio, DM pair production cross section as well as the signal reaches at the LHC. The LHC searches for some visible signals related to the scalar sector are also discussed.

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

“…in [165,[291][292][293]). The DM relic density is determined by annihilation into the SM fermions pairs and, when kinematically accessible, into aa pairs.…”

Fermionic Light Dark Matter Particles and the New Physics of Neutron Stars

“…Apart from the spin-independent interaction model considered before (corresponding to effective scalar and vector couplings), more effective operators for fermionic DM particles can be studied. For example, the so-called Coy Dark Matter model proposed by Boehm et al (2014) which belongs to the family of simplified models, see for instance Dolan et al (2015); Bauer et al (2017); Baek et al (2017), includes two new particles to the SM, i.e. a Dirac fermion DM candidate, χ which interacts with a boson a, with mass m a , through the pseudoscalar coupling of strength g χ as proposed in Arina et al (2015).…”

Universal properties of pseudoscalar mediators in dark matter extensions of 2HDMs

“…1 If the pseudoscalar mediator is a SM singlet, the couplings between SU(2) L 1 A new spin-0 singlet with pseudoscalar couplings to Dark Matter can mix with the SM Higgs, which will lead to spin-0 mass eigenstates which are not CP eigenstates. Such a scenario does not require new states beyond the mediator and dark matter, but is strongly constrained by Higgs coupling measurements [25].…”

“…This effective coupling can be understood as the limit in which additional fermions or scalars beyond the mediator multiplet are integrated out. There is therefore a straightforward way to match UV completions with a more complicated mediator sector [23][24][25] as well as UV completions with the Dark Matter candidate as a component of an electroweak multiplet [29] to the model discussed here.…”