Toward UV models of kinetic mixing and portal matter. VI. A more complex dark matter sector?

Journal Article · Tue Oct 29 00:00:00 EDT 2024 · Physical Review. D.

DOI:https://doi.org/10.1103/PhysRevD.110.075037· OSTI ID:2475429

Rizzo, Thomas G.

Portal matter (PM), having both Standard Model (SM) and dark sector charges, can induce kinetic mixing between the $U(1{)}_D$ dark photon and the SM gauge fields at the 1-loop level offering an attractive mechanism by which light ( $\lesssim 1\mathrm{GeV}$ ) thermal dark matter (DM) can interact with visible matter and obtain its observed relic density. In doing so, if the DM is fermionic, the CMB and other astrophysical observations inform us that it must be Majorana/pseudo-Dirac in nature to avoid velocity/temperature-independent $s$ -wave annihilation to SM final states. How does this idea fit into a more UV-complete picture also including the SM interactions? There are some reasons to believe that at least a first step along this path may not lie too far away in energy due to the renormalization group equations running of the dark gauge coupling, which for a significant range of parameters, becomes nonperturbative at/before the $\sim 10$ ’s of TeV energy range. This implies that $U(1{)}_D$ must become embedded in an asymptotically free, non-Abelian group, $G_D$ , before this can occur. The breaking of this larger group then produces the masses for the PM and the additional gauge fields associated with $G_D$ then can lead to new interactions between the SM and the dark sector. Following several bottom-up approaches, we have examined a set of distinctive and testable phenomenological features associated with this general setup, based upon a number of simplifying assumptions. Clearly, it behooves us to explore the impact of these specific assumptions on these predictions for the array of possible experimental tests of this class of models. In most past analyses it has been assumed that DM is a vectorlike, complex singlet under the group $G_D$ . If this assumption is relaxed, the dark sector must be augmented by additional fermion(s) and the associated scalar fields needed to break the gauge symmetries while generating the needed Majorana-like mass terms for the DM. In this paper, we analyze the simplest extension of this kind wherein the DM lies in a vectorlike doublet of $G_D$ , which we take to have the structure $SU(2{)}_I\times U(1{)}_{Y_I}$ as in earlier work, leading to new phenomenological implications. We find, for example, that given the current LHC search constraints on the masses of heavy gauge bosons, the production of these new dark states with large rates is unlikely to occur at colliders unless they are produced singly in $gg$ fusion or their pair production cross sections are resonantly enhanced. We also find that an additional mechanism arises to generate hierarchal neutrino masses in such a setup. Published by the American Physical Society 2024

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 2475429
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Vol. 110 Journal Issue: 7; ISSN 2470-0010
• Publisher: American Physical Society
• Country of Publication: United States
• Language: English