Radiative magnification of neutrino mixings and a natural explanation of the neutrino anomalies

We show that the neutrino mixing pattern with the large mixing required forthe atmospheric neutrino problem and the small mixing angle MSW solution forthe solar neutrino problem can be naturally generated through radiativemagnification, even though all the mixing angles at the seesaw scale may besmall. This can account for the neutrino anomalies as well as the CHOOZconstraints in the context of quark-lepton unified theories, where the quarkand lepton mixing angles are expected to be similar in magnitude at the highscale. We also indicate the 4$\nu$ mixing scenarios for which this mechanism ofradiative magnification can provide a natural explanation.