Change of Isotopic Spin in the K_(π2) Decay

Abstract

In the slow decays-of hyperons and K-mesons into other strongly interacting particles, isotopic spin I is defined before and after the decay but is not conserved. In fact I changes by half-integers. For all such decays that are known, the rule ΔI_z = ± 1/2 (or = ΔS ± 1. where S is strangeness) seems to obtain (1). In particular, the apparent absence of the process Ξ → π + N is attributed to this rule.

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