2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42877Babu studied the neutrino spectrum obtained when one adds a charged singlet and a doubly charged singlet to the standard model particle spectrum. It was found that the neutrinos acquire a mass matrix at the two-loop level which contains one massless eigenstate. The mass matrix of Babu's model depends on an integral over the undetermined loop momenta. We present the exact calculation of this integral.5 pages, 1 figure; Additional references includedHigh Energy Physics - Phenomenologytext