Supernova axions from nucleons and pions (via Zoom: https://mppmu.zoom.us/j/99300254726)

by Mr Pierluca Carenza (INFN, Bari)

Thursday 26 Nov 2020, 11:00 → 12:00 Europe/Berlin

Zoom (https://mppmu.zoom.us/j/99300254726)

The production channels for QCD axions in a supernova (SN) are nucleon-nucleon (NN) bremsstrahlung and pion-axion conversion. The NN bremsstrahlung process is well-known and in this seminar we revise this calculation including systematically different effects (a non-vanishing mass for the exchanged pion, the contribution from the two-pions exchange, effective in-medium nucleon masses, multiple nucleon scatterings and an arbitrary degree of nucleon degeneracy). Moreover we calculate the axion emission rate from reactions involving thermal pions in SN matter, showing that this contribution is 2-5 times larger than NN bremsstrahlung. The axion spectrum is also found be much harder. Together, the larger rates and higher axion energies imply a stronger bound on the mass of the QCD axion, and better prospects for direct detection in a large underground neutrino detector from a nearby galactic SN.