How neutrinos could help solving cosmological anomalies and tensions

TL;DR

This paper explores how neutrino properties and decays could address various cosmological anomalies and tensions, proposing mechanisms that might be testable in future experiments.

Contribution

It introduces a novel boomerang mechanism involving dark and visible sectors to explain neutrino-related cosmological puzzles.

Findings

Neutrino decays could resolve the neutrino mass tension.

The boomerang mechanism predicts an observable neutrino magnetic moment.

Potential contributions to the 21 cm cosmological signal.

Abstract

In this talk I discuss how neutrinos might help solving or alleviating different anomalies and tensions in cosmology. Invisible decays of the heaviest relic neutrinos might provide a way to solve the neutrino mass tension between cosmological observations and neutrino oscillation experiments. The excess radio background mystery could be explained by radiative decays of relic neutrinos. However, the upper bound on the neutrino effective magnetic moment requires some trick to be circumvented. To this extent, I discuss a recently proposed boomerang mechanism in which the visible sector throws dark neutrinos into the dark sector at $t \sim 100\,{\rm s}$ and $T \sim 100\,{\rm keV}$, and much later (basically at the present time) the dark sector throws back photons into the visible sector. The mechanism predicts an effective neutrino magnetic moment that might be within the reach of next experiments. Some contribution to the 21 cm cosmological signal is also expected. These are exciting times for cosmological searches of BSM physics.