MEASUREMENT OF RATIO OF TAU' PARTIAL DECAY RATES . GAMMA(K- -] PI-PI0PI0)/GAMMA(K+ -] PI+PI0PI0)

A scintillation-counter-optical-spark-chamber arrangement has been used with incident 3.5-BeV/c positive and negative beams at the Argonne National Laboratory Zero-Gradient Synchrotron to study τ′(K±→π±π0π0) decays. A difference between the τ′- and τ′+ partial decay rates would indicate the presence of a CP-violating ΔIÂ52 amplitude in the weak Hamiltonian for these decays. Furthermore, in the absence of electromagnetic interactions, CPT invariance requires that Γ(τ-)+Γ(τ′-)=Γ(τ+)+Γ(τ′+), where τ represents K±→π±π+π- decays. The result found after scanning the film and making small corrections for differences between the detection efficiencies for the two beam polarities was that Γ(τ′-)Γ(τ′+)=1.011±0.018. Also, by combining our result with the results of previous experiments on K→3π decays, it was found that [Γ(τ′)+Γ(τ′-)][Γ(τ+) +Γ(τ′+)]-1=0.0029±0.0045. © 1969 The American Physical Society.