Upper limits on the branching ratios tau --> mu gamma and tau --> e gamma

The DELPHI collaboration has searched for lepton flavour violating decays τ → μγ and τ → μgg using a data sample of about 70 pb−1 of integrated luminosity corresponding to 81 000 produced τ+τ− events. No candidates were found for either of the two modes. This yields branching ratio upper limits of B(τ → eγ) < 1.1 × 10−4 and B(τ → μγ) < 6.2 × 10−5 at 90% confidence level.