Abstract
Recent observations suggest that the number of relativistic degrees of freedom in the early universe might exceed what is predicted in the standard cosmological model. If even a small, percent-level fraction of dark matter particles are produced relativistically, they could mimic the effect of an extra realistic species at matter-radiation equality while obeying BBN, CMB and Structure Formation bounds. We show that this scenario is quite naturally realized with a weak-scale dark matter particle and a high-scale ``mother'' particle within a well motivated 3-3-1 gauge model, which is particularly interesting for being consistent with electroweak precision measurements, with recent LHC results, and for offering a convincing explanation for the number of generations in the Standard Model.
Highlights
Dark Matter is compelling evidence for new physics beyond the Standard Model
This study is organized as follows: we review the notion that WIMPs produced in a relativistic state can act effectively as “dark radiation”; III we outline the particular particle physics setup we will hone in for the present analysis: the 3-3-1LHN model; section IV describes in general how dark radiation is realized in the context of 3-3-1LHN models, while section V examines in detail the relevant parameter space
Funded by SCOAP3 / License Version CC BY 4.0. It has been proposed recently in the literature that some fraction of the dark matter particles produced nonthermally could mimic the effect of additional relativistic neutrino species
Summary
Dark Matter is compelling evidence for new physics beyond the Standard Model. Observations from a variety of experiments and physical scales have conclusively established the existence of dark matter. We show that such a scenario may arise with a weakscale WIMP in the context of a non-supersymmetric 3-31 model, an electroweak extension of the Standard Model (SM) featuring a gauge group SU (3)c ⊗ SU (3)L ⊗ U (1)N This model is a compelling alternative to the SM with a smoking gun signature given by the presence of charged gauge bosons and scalars, as well as a spectrum of particles whose phenomenological aspects have been investigated extensively [23,24,25,26,27,28,29,30,31]. This study is organized as follows: we review the notion that WIMPs produced in a relativistic state can act effectively as “dark radiation”; III we outline the particular particle physics setup we will hone in for the present analysis: the 3-3-1LHN model; section IV describes in general how dark radiation is realized in the context of 3-3-1LHN models, while section V examines in detail the relevant parameter space.
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