ΔI = 3/2 and ΔS = 2 hyperon decays in chiral perturbation theory

We study the |ΔI| = 3/2 and |ΔS| = 2 amplitudes for hyperon decays of the form B → B′π at lowest order in chiral perturbation theory. At this order, the ΔI = 3/2 amplitudes depend on only one constant. We extract the value of this constant from experiment and find a consistent description of these processes at the 2σ level. The same constant determines the ΔS = 2 transitions which, in the standard model, are too small to be observed. We find that new physics with parity odd ΔS = 2 interactions can produce observable rates in hyperon decays while evading the bounds from K⁰-K̄⁰ mixing.