Particle Seminar

Monday, May 27, 2019

Speaker: Maíra Dutra

Affiliation: Carleton

Time: 2:30PM -- 3:30PM

Location: HP 4351

Title: Early genesis of dark matter particles: the FIMP wonder

Abstract: The nature of dark matter (DM), which is more likely to be made out of
particles, is one of the biggest mysteries in the interface between
particle physics and cosmology. The current status of searches for DM
particles point out to a complex dark sector and indicates that DM and SM
particles interact very weakly. If their interactions are too weak, the
dark and visible sectors were never in thermal equilibrium in the early
universe, as needed in the standard production mechanism, the thermal
freeze-out. In this talk, based on the work I have done in my Ph.D, I
consider the feebly interacting massive particles (FIMPs), which are DM
candidates produced from the SM thermal bath in out-of-equilibrium
processes (freeze-in). Heavy fields (10^{10}-10^{16} GeV) are needed in
many fundamental extensions of the SM in the cosmological context, as for
instance GUT, seesaw and inflation, and their exchange between the visible
and dark sectors is therefore an appealing underlying reason for the
feeble interactions. Such a connection, which makes the freeze-in at the
earliest stages of the radiation era a reasonable possibility, is what I
have called the "FIMP wonder". I discuss different realizations of the
"FIMP wonder", with models involving moduli, fermions, gauge bosons and
spin-2 fields as heavy mediators. Finally, I will show that if the heavy
mediators were produced on-shell whithin a period of entropy production in
the early universe, as in the post-inflationary reheating, the relic
density of dark matter may be enhanced by many orders of magnitude
relative to the standard isentropic expansion of the universe.