Light and darkness: consistently coupling dark matter to photons via effective operators

Abstract

We consider the treatment of fermionic dark matter interacting with photons via dimension-5 and -6 effective operators, arguing that one should always use hypercharge gauge field form factors, instead of those of the photon. Beyond the simple observation that the electromagnetic form factor description breaks down at the electroweak scale, we show how the additional couplings to the Z boson predicted by the hypercharge form factors modify the relic density calculation and indirect detection limits for dark matter masses of a few tens of GeV and above. Furthermore, constraints from the invisible Z decay width can be competitive for masses below 10 GeV. We review the phenomenology of hypercharge form factors at the LHC as well as for direct and indirect detection experiments. We highlight where the electromagnetic and hypercharge descriptions lead to wildly different conclusions about the viable parameter space and the relative sensitivity of various probes, namely vector boson fusion versus mono-jet constraints from the LHC, and indirect versus direct searches, for larger dark matter masses. We find that the dimension-5 operators are strongly constrained by direct detection bounds, while for dimension-6 operators LHC mono-jet searches are competitive or better than the other probes we consider.

Thermal WIMPs and the scale of new physics: global fits of Dirac dark matter effective field theories

“…For a recent discussion of LHC constraints on these operators we refer to Ref. [75]. 2 These constraints also ensure that the dimension-six operators do not explicitly break electroweak symmetry, which requires C (6) 1,u − C (6) 3,u = C (6)…”

Freezing In with lepton flavored fermions

“…There exist FIMP models that derive constraints from indirect detection experiments [14,100], CMB and astrophysics experiments [48,50,[101][102][103][104], and at colliders [105,106]. However, we estimate that these constraints do not probe the models studied in this work [107][108][109][110][111]. Neutron star constraints [112] are not able to probe these models either because they probe much heavier masses or because the capture rate is suppressed due to the large velocity of DM particles near the neutron star surface.…”

Portal Effective Theories. A framework for the model independent description of light hidden sector interactions

“…For example, this is the case of fermionic DM models that couple to the SM via four-fermion interactions of dimension six, see e.g. [172,173]. In addition, higher dimensional portal operators can mediate transitions that are not captured by lower dimensional portal operators.…”