In this article, we have considered an extension of the inert Higgs doublet model with SU (2)L singlet vector like fermions. Our model is capable of addressing some interesting anomalous results in b → s + − decays (like R(K ( * ) )) and in muon (g − 2). Apart from explaining these anomalies, and being consistent with other flavour data, the model satisfies relevant constraints in the dark matter sector, while remaining within the reach of ongoing direct detection experiments. The model also produces signatures at the large hadron collider (LHC) with final states comprised of dilepton, dijet and missing energy, providing signals to be probed at higher luminosity.

We perform a model independent study of freeze-in of massive particle dark matter (DM) by adopting an effective field theory framework. Considering the dark matter to be a gauge singlet Majorana fermion, odd under a stabilising symmetry Z2 under which all standard model (SM) fields are even, we write down all possible DM-SM operators upto and including mass dimension eight. For simplicity of the numerical analysis we restrict ourselves only to the scalar operators in SM as well as in the dark sector. We calculate the DM abundance for each such dimension of operator considering both UV and IR freeze-in contributions which can arise before and after the electroweak symmetry breaking respectively. After constraining the cut-off scale and reheat temperature of the universe from the requirement of correct DM relic abundance, we also study the possibility of connecting the origin of neutrino mass to the same cut-off scale by virtue of lepton number violating Weinberg operators. We thus compare the bounds on such cut-off scale and corresponding reheat temperature required for UV freeze-in from the origin of light neutrino mass as well as from the requirement of correct DM relic abundance. We also briefly comment upon the possibilities of realising such DM-SM effective operators in a UV complete model.

We study the impact of thermalization and number-changing processes in the dark sector on the yield of gravitationally produced dark matter (DM). We take into account the DM production through the s-channel exchange of a massless graviton both from the scattering of inflatons during the reheating era, and from the Standard Model bath via the UV freeze-in mechanism. By considering the DM to be a scalar, a fermion, and a vector boson we show, in a model-independent way, that DM self-interaction gives rise to a larger viable parameter space by allowing lower reheating temperature to be compatible with Planck observed relic abundance. As an example, we also discuss our findings in the context of the ℤ2-symmetric scalar singlet DM model.

An SU (2) N extension (N stands for neutral) of the Standard Model (SM) is proposed with an additional U (1) = S global symmetry, which stabilizes the lightest of the vector boson (X,X) as dark matter (DM) through unbroken S = T 3N + S . The field content of the model is motivated to address neutrino mass generation, a possible unification to SU (7), along with spontaneous symmetry breaking of SU (2) N resulting in massive gauge bosons. None of the SM particles are charged under SU (2) N and therefore X,X do not have a direct coupling to the visible sector besides a Higgs portal, which is tiny to avoid any conflict with Higgs data. We show that, a large kinematic region of this model allows the neutral component of SU (2) N scalar triplet and heavy neutrinos introduced here to become additional DM components. In this paper we explore the viability of such multipartite DM parameter space, including non-zero DM-DM interactions, to comply with relic density and direct search constraints. We also demonstrate that the model may yield hadronically quiet single lepton and two lepton signatures with missing energy at the Large Hadron Collider (LHC) that can be accessed with high luminosity.