K0S production in τ decays

From a sample of about 160k Z → τ+τ- candidates collected with the ALEPH detector at LEP between 1991 and 1995, τ lepton decays involving K0S → π+π- are studied. The K0SK0L associated production in τ decays is also investigated. The branching ratios are measured for the inclusive decay B(τ-→K0SX-ν τ) = (9.70±0.58±0.62) × 10-3, where X- can be anything, and for the exclusive decays B(τ-→K̄0π-ν τ) = (8.55±1.17±0.66) × 10-3, B(τ-→K̄0π-π 0ντ) = (2.94±0.73±0.37) × 10-3, B(τ-→K̄0K-ντ) = (1.58±0.42±0.17) × 10-3, B(τ-→K̄0K-π 0ντ) = (1.52±0.76±0.21) × 10-3. The decay τ-→K0SK0 Lπ-ντ is studied for the first time, giving a branching ratio B(τ-→K0SK0 Lπ-ντ) = (1.01±0.23±0.13) × 10-3. The channels τ- → K0SK0Sπ-ν τ , τ- → K0SK0Sπ-π 0ντ , τ- → K0SK0Lπ-π 0ντ , τ- → K̄0π-π0π0ν τ, τ-→K0K-π0π 0ντ and τ-→K0h+h-h -ντ are also investigated. In addition, mass spectra in the K0Sh- and K0Sh-π0 final states are analysed to provide information on the intermediate states produced in the decays.