μ→e+γ and τ→μ+γ decays in string models withE6symmetry

${\mathit{E}}_6$ string models for which (i) ${\mathrm{E}}_6$ breaks to [SU(3)${]}^3$ at the Planck scale, (ii) [SU(3)${]}^3$ breaks to SU(3)×SU(2)×U(1) at an intermediate scale ${\mathit{M}}_{\mathit{I}}$ triggered by a (mass${)}^2$ ${\mathit{m}}^2$<0 where ≲1 TeV, and (iii) the model possesses a matter-parity invariance lead to the new-physics signals of μ→eγ and τ→μγ decays which may be accessible experimentally. The outgoing lepton is nearly 100% right handed and the τ→μγ branching ratio about ${10}^5$ times larger than the μ→eγ. Possible ways of detecting these decays are discussed.