Tanner Trickle (Caltech)
Multi-Channel Searches for Light Dark Matter
Abstract: As the search for dark matter (DM) continues, direct detection experiments will be sensitive to a broad range of DM candidates with sub-GeV masses. To detect this light DM the current, and next, generation of direct detection experiments will be based on detection channels other than nuclear recoil. In this talk I will discuss electron, phonon, and magnon excitations; each of which are planned to be experimentally realized. Beginning with electronic excitations I will discuss extensions to the DM scattering rate calculation, and a new formulation of the DM absorption rate calculation using a non-relativistic effective field theory (NR EFT). Both of these theoretical improvements have important consequences for certain DM models when interacting with semiconducting (e.g., silicon and germanium) crystal targets. Collective excitations, e.g., phonons and magnons, have modes at energies lower than the electron band gap and will provide complementary probes of even lighter DM candidates. I will present an EFT description of DM-phonon and magnon interaction rates in a general crystal target, and discuss how first principles calculations can be used to maximize the coverage of DM model space once these experiments are operational.
Maíra Dutra (Carleton)
Testing freeze-in with Z' bosons
Abstract: Dark matter particles can interact so weakly with the standard
model fields that they may never have reached thermal equilibrium in the
early universe. The relic density of such feebly interacting massive
particles (FIMPs) is produced via the so-called freeze-in mechanism.
This possibility can explain why we have not detected dark matter yet,
but is also appealing from a theoretical perspective since tiny
couplings might be a consequence of heavy particles needed to solve
different puzzles in particle physics. In this talk, I will overview
the literature on FIMP phenomenology and present a testable Z' portal
model of FIMP dark matter. In our model, all the standard fermions and a
fermionic FIMP candidate are charged under a new U(1) symmetry.
Remarkably, the rich phenomenology of Z' bosons is currently constraining
regions of the Z' parameter space in which the dark matter relic density
is achieved via freeze-in.