Orateur
Description
A new tension is starting to emerge between the tight cosmological upper bounds on the total neutrino mass and the lower limits from oscillation data, with potentially far-reaching implications for cosmology and particle physics. Invisible neutrino decays provide a compelling particle physics scenario to explain this tension. In this talk, I will present updated constraints on a framework where neutrinos decay non-relativistically into dark radiation, showing that the mass bound from Planck 2018+DESI BAO DR2 is relaxed to $\sum m_\nu < 0.24 \ \rm{eV}$, in full agreement with oscillation data. I will also report the first late-time cosmological analysis of neutrino decays consistent with the measured mass splittings, showing that this scenario can only slightly alleviate the mass bounds. These results were possible thanks to new neural network emulators, which are ~200 times faster than the full Boltzmann solutions. I will end by discussing how future experiments aiming at directly detecting the cosmic neutrino background (e.g., PTOLEMY) have great potential to probe invisible neutrino decays.
