Conveners
Light and dark particles
- Francesco D'Eramo (University of Padua)
We conduct a general study of the various constraints on the existence of primordial high-energy neutrinos (PHENu), emitted as early as the neutrino decoupling era and propagating through the Universe nearly unaltered since their emission. We explore the parameter space in which such neutrinos could be detected and confront our findings with current cosmological and observational constraints.
We consider an extended seesaw model which generates active neutrino masses via the usual type-I seesaw and leads to a large number of massless fermions as well as a sterile neutrino dark matter (DM) candidate in the O(10−100) keV mass range. The dark sector comes into thermal equilibrium with Standard Model neutrinos after neutrino decoupling and before recombination via a $U(1)$ gauge...
Axions can be produced via the interactions in the thermal plasma
of the early Universe and their contribution to dark radiation can
modify the cosmological observables and constrain the axion
couplings to SM particles. In my talk I am going to outline an
approach to calculate the axion cosmological abundance that goes
beyond the approximations widely used in the literature on the
topic...
In this talk I present the cosmological consequences of axion interactions with standard model fermions accurately and precisely. Our analysis is entirely based on a phase space framework that allows us to keep track of the axion distribution in momentum space across the entire expansion history. First, we consider flavor-diagonal couplings to charged leptons and quantify the expected amount...
Previous studies on the production of feebly interacting particles have encountered challenges due to negative interaction rates at soft momenta. We resolve this issue by investigating the thermal production of Axion-Like Particles (ALPs) from the freeze-in mechanism via feeble interactions with U(1) gauge fields, employing the full 1PI-resummed gauge boson propagator. This approach ensures a...
