Lepton flavour violation in a supersymmetric model with A(4) flavour symmetry

We compute the branching ratios for μ→eγ, τ→μγ and τ→eγ in a supersymmetric model invariant under the flavour symmetry group A4×Z3×UFN(1), in which near tri-bimaximal lepton mixing is naturally predicted. At leading order in the small symmetry breaking parameter u, which is of the same order as the reactor mixing angle θ13, we find that the branching ratios generically scale as u2. Applying the current bound on the branching ratio of μ→eγ shows that small values of u or are preferred in the model for mass parameters mSUSY and m1/2 smaller than 1000 GeV. The bound expected from the on-going MEG experiment will provide a severe constraint on the parameter space of the model either enforcing u≈0.01 and small or mSUSY and m1/2 above 1000 GeV. In the special case of universal soft supersymmetry breaking terms in the flavon sector a cancellation takes place in the amplitudes and the branching ratios scale as u4, allowing for smaller slepton masses. The branching ratios for τ→μγ and τ→eγ are predicted to be of the same order as the one for μ→eγ, which precludes the possibility of observing these τ decays in the near future.