MU-] E+GAMMA AND TAU-MU+GAMMA DECAYS IN STRING MODELS WITH E6 SYMMETRY

E6 string models for which (i) E6 breaks to [SU(3)]3 at the Planck scale, (ii) [SU(3)]3 breaks to SU(3) x SU(2) x U(1) at an intermediate scale M(I) triggered by a (mass)2 m2 < 0 where m less-than-or-similar-to 1 TeV, and (iii) the model possesses a matter-parity invariance lead to the new-physics signals of mu --> e-gamma and tau --> mu-gamma decays which may be accessible experimentally. The outgoing lepton is nearly 100% right handed and the tau --> mu-gamma branching ratio about 10(5) times larger than the mu --> e-gamma. Possible ways of detecting these decays are discussed.