Upper limits for the decay of τ-leptons intoη-mesons

Abstract

The production of η-mesons in τ-decays has been studied with the ARGUS detector at the DORIS II storage ring. τ⁺τ⁻ events were selected by their characteristic 1-versus-3 charged particle topology. The π⁺π⁻ invariant mass distribution was used to search for evidence of η production in τ-decays. No signal was observed, leading to upper limits at 95% CL of Br(τ⁻→ηπ⁻π⁰ v _τ)<1.1%, Br(τ⁻→ηηπ⁻ v _τ)<0.8%, Br(τ⁻→ηηπ⁻π⁰ v _τ)<0.9% and Br(τ⁻→ηπ⁻π⁰π⁰ v _τ)<1.2%. A search for the decay τ⁻→ηπ⁻ v _τ, where the π⁰ from the decay η→π⁺π⁻π⁰ is also reconstructed, yield an upper limit at 95% CL of Br(τ⁻→ηπ⁻ v _τ)<0.9%. In addition, the inclusive value (1.65±0.3±0.2)% for Br(τ⁻→ωX ⁻ v _τ) follows from this analysis.