Electron-neutrino Majorana mass and solar neutrino oscillations

Assuming the Majorana masses of nu(e) and the linear combination c nu(tau) - s nu(mu) to be equal from their couplings to a heavy scalar triplet xi, I show that their radiative splitting is given by Delta m(2)/m(nu)(2) = (3c(2)/4 pi(2))(G(F)/root 2)m(tau)(2)ln(m(xi)(2)/m(w)(2)). This is applicable to the small-angle matter-enhanced oscillation solution of the solar neutrino deficit and restricts m(nu) to be between 0.20 and 0.36 eV if c(2) = 0.7 and m(xi) = 10(14) GeV. (C) 1999 Elsevier Science B.V. All rights reserved.