Abstract
A model of dark matter (DM) that communicates with the Standard Model (SM) exclusively through suppressed dimension five operator is discussed. The SM is augmented with a symmetry U(1)X ⊗ Z2, where U(1)X is gauged and broken spontaneously by a very heavy decoupled scalar. The massive U(1)X vector boson (Xμ) is stabilized being odd under unbroken Z2 and therefore may contribute as the DM component of the universe. Dark sector field strength tensor Xμν couples to the SM hypercharge tensor Bμν via the presence of a heavier Z2 odd real scalar Φ, i.e. 1/Λ XμνBμνΦ, with Λ being a scale of new physics. The freeze-in production of the vector boson dark matter feebly coupled to the SM is advocated in this analysis. Limitations of the so-called UV freeze-in mechanism that emerge when the maximum reheat temperature TRH drops down close to the scale of DM mass are discussed. The parameter space of the model consistent with the observed DM abundance is determined. The model easily and naturally avoids both direct and indirect DM searches. Possibility for detection at the Large Hadron Collider (LHC) is also considered. A Stueckelberg formulation of the model is derived.
Highlights
Since no Standard Model (SM) particle resembles the properties of a dark matter (DM) particle, many possibilities beyond the SM (BSM) have been formulated to explain the particle nature of the DM, as scalar, fermion or a vector boson stabilized by an additional symmetry GDM
Since we are interested in the freeze-in production of the DM, we look for all such number changing processes with at least one DM particle in the final state
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 Ultra Violet (UV) freeze-in [50, 82] limit, where the DM abundance is sensitive to the reheat temperature TRH of the universe and new physics (NP) scale Λ only
Summary
The minimal VDM model contains a U(1)X gauge boson denoted here by Xμ. In order to enable direct interactions between Xμ and the SM one requires presence of a real scalar Φ Both of them should be odd under a Z2 which stabilises DM candidate, i.e. the vector boson (mX < mΦ). In order to generate a mass for the dark gauge boson we introduce a complex scalar S charged under U(1)X , which acquires a vacuum expectation value to break U(1)X spontaneously. The quantum numbers under SU(3)c × SU(2)L × U(1)Y × Z2 of the new fields are tabulated in table 1. We expect to reproduce a version of the Stueckelberg model coupled to the extra scalar Φ and the SM Higgs doublet H.
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