Speaker
Angus Spalding
(Univeristy of Southampton)
Description
I will show that spectral features of a gravitational-wave background can probe type-I seesaw parameters, independently of the gravitational-wave production mechanism. Long-lived Right-Handed Neutrinos generically induce a temporary period of early matter domination in the thermal history of the Universe, which imprints a feature in any primordial gravitational-wave background, characterised by two frequencies corresponding to the onset and end of this epoch. These frequencies are determined by the initial abundance, mass, and decay rate of the dominating species. I will explore how this mechanism is realised through non-thermal production of right-handed neutrinos in the minimal type-I seesaw, and separately the gauged $U(1)_{B-L}$ model.
Authors
Angus Spalding
(Univeristy of Southampton)
Dr
Anish Ghoshal
(University of Sussex)
Dr
Graham White
(Univeristy of Southampton)