Chinese Ctr Adv Sci & Technol, World Lab, Beijing 100080, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
We examine whether an appreciable value of the lepton flavor mixing angle theta(13) at the electroweak scale Lambda(EW) can be radiatively generated from theta(13)=0degrees at the grand unified theory (GUT) scale Lambda(GUT). It is found that the renormalization-group running and seesaw threshold effects may lead to theta(13)similar to5degrees at low energies for two simple large-maximal mixing patterns of the Maki-Nakagawa-Sakata matrix in the minimal supersymmetric standard model. If theta(12) is sufficiently large at Lambda(GUT), it will be possible to radiatively produce theta(13)similar to5degrees at Lambda(EW) both in the standard model and in its supersymmetric extensions. The mass spectrum of three heavy right-handed Majorana neutrinos and the cosmological baryon number asymmetry via leptogenesis are also calculated.