Speaker
Description
A strong first-order phase transition offers the intriguing possibility of explaining the stochastic gravitational wave background at nHz frequencies. In order to avoid cosmological constraints, such a phase transition must have occurred in a dark sector with non-negligible couplings to the standard model - opening promising avenues of
connecting the gravitational wave signal to the cosmological dark matter abundance. In order to illustrate this, I will consider a classically conformal dark sector with a U(1) gauge symmetry. The spontaneous breaking of this symmetry generates both gravitational waves and sources the mass of a fermionic sub-GeV dark matter candidate. Contact with the standard model is established through kinetic mixing of the U(1) gauge bosons with ordinary photons, a possibility that is actively being searched for at various collider experiments. I will discuss the rich phenomenology of such a scenario, demonstrating that it can successfully generate both the observed nHz gravitational wave background and the cosmological dark matter abundance, while at the same time avoiding all current constraints.
| Main Contribution topic | Cosmology Dark Matter |
|---|---|
| Secondary contribution topic | Theory / Phenomenology |