Stealth decaying spin-1 dark matter

Abstract

We consider models of decaying spin-1 dark matter whose dominant coupling to the standard model sector is through a dark-Higgs Yukawa portal connecting a TeV-scale vector-like lepton to the standard model (right-handed) electron. Below the electron-positron threshold, dark matter has very slow, loop-suppressed decays to photons and (electron) neutrinos, and is stable on cosmological time-scale for sufficiently small gauge coupling values. Its relic abundance is set by in-equilibrium dark lepton decays, through the freeze-in mechanism. We show that this model accommodates the observed dark matter abundance for natural values of its parameters and a dark matter mass in the ∼ 5 keV to 1 MeV range, while evading constraints from direct detection, indirect detection, stellar cooling and cosmology. We also consider the possibility of a nonzero gauge kinetic mixing with the standard model hypercharge field, which is found to yield a mild impact on the model’s phenomenology.

New leptons with exotic decays: collider limits and dark matter complementarity

“…Even more interestingly, the possibility of simultaneously having both types of decays, into a SM lepton plus a W , Z or Higgs boson and into a SM lepton and missing energy, has never been considered in the past, despite the fact that this possibility is easy to realize and is even well motivated in the context of feebly interacting DM [28]. In this article we consider the possibility that the new VLL can simultaneously decay into the usual SM final states as well as into a SM lepton and missing energy.…”

“…In this case, the DM candidate is not in equilibrium with the thermal bath but is actually produced through the decay of other heavy particles, in our case, the decay of the VLL. This possibility has been recently explored in [28] with emphasis on the DM phenomenology, thus setting the VLL mass to a conservative M E = 1 TeV in order to avoid any collider constraint. In this subsection we aim to show the complementarity between DM experiments and the collider results we presented before for a FIMP.…”

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

“…More accurate tools in the form of Lyman-α likelyhoods[60] have not yet been applied to freeze-in 3. For a FI model with instead spin-1 DM produced by the decay of a long-lived vectorlike lepton, see[62].…”

A multi-temperature universe can allow a sub-MeV dark photon dark matter

“…The formalism noted above is used in the investigation of a dark photon and dark fermions of hidden sectors as possible DM candidates. There exists a considerable literature in the study of dark photons [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] (for review see [19][20][21]) to which the interested reader JHEP06(2021)086 is directed. While axions and dark photons in the light to ultralight mass region (from keV to 10 −22 eV) have been investigated [11,13,[22][23][24][25][26], the sub-MeV dark photon mass range appears difficult to realize.…”