Résumé
In models with left-right symmetry, type I and II seesaw mechanisms contribute to the light neutrino mass matrix m in a correlated way, via the Higgs triplet Yukawa coupling matrix f. Once m is fixed, we show that a given structure of f satisfies the seesaw formula if and only if ≡ m − f does. We investigate the consequences of this seesaw duality . Preprint SACLAY-T05/180