Prospects for an accurate measurement of the branching ratio π0 → e+e−/π0 → all

Abstract

The π0 → e+e− branching ratio has been the subject of two recent measurements, each with quoted errors of ± 35% or greater. The results are mutually consistent but 3–4 times larger than any conventional theory can accommodate. Outlined in this paper is a method that can potentially achieve an unambiguous measurement accurate to ± 5% by normalization to a well-understood internal-conversion process.