2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/178891If neutrino masses and mixings are suitable to explain the atmospheric and solar neutrino fluxes, this amounts to contributions to FCNC processes, in particular mu --> e, gamma. If the theory is supersymmetric and the origin of the masses is a see-saw mechanism, we show that the prediction for BR(mu --> e, gamma) is in general larger than the experimental upper bound, especially if the largest Yukawa coupling is O(1) and the solar data are explained by a large angle MSW effect, which recent analyses suggest as the preferred scenario. Our analysis is bottom-up and completely general, i.e. it is based just on observable low-energy data. The work generalizes previous results of the literature, identifying the dominant contributions. Application of the results to scenarios with approximate top-neutrino unification, like SO(10) models, rules out most of them unless the leptonic Yukawa matrices satisfy very precise requirements. Other possible ways-out, like gauge mediated SUSY breaking, are also discussed.42 pages, LaTeX, 13 PS figures. References added and minor details correctedHigh Energy Physics - Phenomenologytext