On the validity of chiral perturbation theory for weak hyperon decays

Abstract

The predictions of chiral perturbation theory for the weak non-leptonic decays of hyperons are examined beyond the leading order. For the S-wave amplitudes we find that the leading corrections to lowest order chiral perturbation theory preserve the vanishing of the Σ + → nπ + amplitude. However, the Lee-Sugawara relation gets a large correction indicating a breakdown of chiral perturbation theory for this relation. For the P-wave amplitudes we find that the leading corrections to lowest order chiral perturbation theory are large indicating a breakdown of chiral perturbation theory for the P-wave amplitudes. The weak semileptonic hyperon decays are determined by baryon matrix elements of the left-handed current. Corrections to the predictions of lowest order chiral perturbation theory for these matrix elements are computed. These corrections are very small.