Neutrino mass operator renormalization revisited

We re-derive the renormalization group equation for the effective coupling of the dimension five operator which corresponds to a Majorana mass matrix for the Standard Model neutrinos. We find a result which differs somewhat f rom, earlier calculations, leading to modifications in the evolution of lep tonic mixing angles and CP phases. We also present a general method for cal culating beta -functions from counterterms in MS-like renormalization schem es, which works for tensorial quantities. (C) 2001 Elsevier Science B.V. Al l rights reserved.