Determination of the branching ratiosΓ(K _L→3π⁰)/Γ(K _L→π^{+ - 0}) andΓ(K _L→3π⁰)/Γ(K _L→πev)

Abstract

Improved branching ratios were measured for theK _L→3π⁰ decay in a neutral beam at the CERN SPS with the NA31 detector:

$$\Gamma ({\rm K}_L \to 3\pi ^0 )/\Gamma ({\rm K}_L \to \pi ^ + \pi ^ - \pi ^0 ) = 1.611 \pm 0.037$$

and

$$\Gamma ({\rm K}_L \to 3\pi ^0 )/\Gamma ({\rm K}_L \to \pi ev) = 0.545 \pm 0.010.$$

From the first number an upper limit for ΔI=5/2 and ΔI=7/2 transitions in neutral kaon decay is derived. Using older results for the Ke3/Kμ3 fraction, the 3π⁰ branching ratio is found to beΓ(K _L →3π⁰)/Γ _tot =(0.211±0.003), about a factor three more precise than from previous experiments.