Tau signals of R-parity breaking at LEP 200

Abstract

The detectability at LEP 200 of explicit R-parity breaking by tau-number (L_τ) violating operators is considered. The assumption of L_τ-violation is motivated by the relative lack of constraints on such coupling but similar considerations apply to explicit L_e or Lμ-violation. The LSP, now unstable, and not necessarily neutral, decays via L_τ-violating modes. Only signals from the production and decays of LSP pairs are considered, thereby avoiding any dependence on the sparticle mass spectrum. Rather spectacular signals are predicted: spherical events with m leptons (usually containing at least one τ) and n jets (m, n ≤ 4), the most characteristic of which are like-sign ττ events. These signals are enumerated for each LSP candidate and quantitative estimates are provided for the favoured case when the LSP is a neutralino. Other new physics signals, which can mimic these signatures, are also briefly discussed.