Speaker
Description
In this talk I will present a new potential signature of supernovae axion-like particles (ALPs) in neutrino water Cherenkov detectors. If ALPs couple to protons, then they can be detected through ALP absorption on free protons, $a\ p→p\ γ$, where the resulting photon has approximately the energy of the ALP. This new signature is complementary to the usual one from oxygen de-excitation, and can be exploited in various ways.
I will first argue that ALPs with MeV masses can be produced with semi-relativistic velocities in core-collapse galactic supernovae and that they can constitute a diffuse flux formed by the overlap of the ALP fluxes. Using Super-Kamiokande data, new constraints on the ALP-proton coupling can be derived in regions that cooling bounds cannot probe. For lighter ALPs, the conditions for a diffuse flux fail. Nevertheless, they can still be looked for on individual (future) neighbouring supernovae. I will show that this new signature, combined with the one expected from oxygen de-excitation, would allow us to disentangle ALP-neutron and ALP-proton couplings.
