We investigate the effects of a mixing of active and sterile neutrinos on the
ratios of supernova electron neutrino flux (Fe) and antineutrino flux
(Feˉ) to the total flux of the other neutrino and antineutrino
flavours (Fa). We assume that the heaviest (in the normal hierarchy)
Standard Model neutrino ν3 mixes with a sterile neutrino resulting in a
pair of mass eigenstates with a small mass gap. Using the density matrix
formalism we solve numerically the the evolution of neutrino states in the
envelope of a supernova and determine the flux ratios Fe/Fa and
Feˉ/Fa as a function of the active-sterile mixing angle and for the
experimentally allowed range of the standard active-active mixing angle
θ13.Comment: 5 pages, 3 figures. This is the corrected version to be published in
Physical Review