Effective theory of freeze-in dark matter

Abstract

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.

Displaced new physics at colliders and the early universe before its first second

“…The value d = 4.5 divides two distinct regimes, and DM production is more efficient at high temperatures for d > 4.5. This case, where the interaction is non-renormalizable, is often referred to as UV freeze-in [43][44][45][46]. On the contrary, for renormalizable operators scatterings dominate over decays only if a larger number of scattering processes can contribute to DM production or when the mass splitting between B and X is small enough to suppress the decay rate (see e.g.…”

Feebly coupled vector boson dark matter in effective theory

“…In this section, we demonstrate the difference between massless and massive limit of DM production cross-section and therefore we will be able comment on limitations of the Ultra Violet (UV) freeze-in advocated in [50,82]. Here we limit ourself to the period before EWSB so all the SM particles are massless.…”

“…which we will use to find the relic density allowed parameter space of the model. Since in our case the connection between the dark and the visible sector proceeds via a non-renormalizable interaction, the DM abundance is usually characterized by UV freeze-in [50,82] limit, where the DM abundance is sensitive to the reheat temperature T RH of the universe and NP scale Λ only. This is in sharp contrast to the Infra-Red or IR freeze-in scenario where the two sectors communicate via renormalizable operators, and the DM abundance is set by the IR physics i.e.…”

FIMP Dark Matter in Clockwork/Linear Dilaton extra-dimensions

“…However, the strength of the DM gravitational interaction could be tiny enough that DM particles are feebly interacting massive particles (FIMP's) and, thus, the relic abundance of DM is set via the DM freeze-in production mechanism [27][28][29][30][31][32], instead (for a recent review see ref. [33]).…”