Charged lepton flavour violation from inverse seesaw with flavour and CP symmetries

Abstract: We study charged lepton flavour violation in a scenario in which light neutrino masses are generated via the inverse seesaw mechanism with 3+3 gauge singlet fermions, Ni and Sj, i,j=1,2,3. Lepton mixing is predicted with the help of the flavour symmetries Delta (3 n^2) and Delta (6 n^2) combined with CP. In the neutral lepton sector, the non-trivial flavour structure is only encoded in the Dirac neutrino Yukawa matrix (the coupling relating left-handed lepton doublets and gauge singlets Ni). Current experimental bounds on the processes mu -> e gamma, mu -> 3 e, mu-e conversion in nuclei and the tau lepton decays tau -> l gamma and tau -> 3 l, l=e, mu, do not constrain the considered parameter space of this scenario. Prospective limits on the decay mu -> 3 e and mu-e conversion in aluminium instead can markedly reduce the available parameter space. We also comment on the effects of the heavy sterile states on light neutrino masses and lepton mixing.