New approach to neutrino masses and leptogenesis with Occam's razor
Abstract
The minimal type-I seesaw framework with texture-zero Yukawa and mass matrices inspired by Occam's razor is incompatible with normally-ordered neutrino masses (currently preferred by data) when lepton mixing originates solely from the neutrino sector. Moreover, the lightest right-handed neutrino mass required to generate the observed baryon asymmetry of the Universe via leptogenesis (M1 1014 GeV) is in conflict with vanilla scenarios for Peccei-Quinn) axion dark matter where the reheating temperature of the Universe is typically below 1012 GeV. In this work, we present a new Occam's razor setup which overcomes these problems by including charged-lepton mixing parametrized by a single angle, which is predicted to be very close to the quark Cabibbo angle. Furthermore, the atmospheric mixing angle lies in the second octant and the leptogenesis scale is lowered to 5.5× 1010 GeV, lifting the tension with the axion dark-matter hypothesis.