Gyo Takeda

Low-energy theorem for exchange axial-vector currents

Abstract A low-energy theorem is given for the two-body exchange current of axial-vector type. The exchange current is divided into two parts, the one directly related to the nuclear forces and the remainder, and the numerical results for the former are shown to be in good agreement with experiments for the beta decay of triton.

Conservation Laws in the Isotopic Spin Space and Their Violation by the Electromagnetic Interaction

The SIGMA /sup +/- SIGMA /sup -/ mass difference and the electromagnetic correction on the DELTA I = 1/2 law for non-leptonic hyperon snd K-meson decays are discussed, based on the assumption of charge independence for strong interactions. Simple calculation for the two phenomena reveals the difficulty that larger electromagnetic effects are needed. Various approximate conservation laws in the isotopic spin space and their implications for the understanding of non-leptonic decays are likewise discussed. (auth)

Complete symmetry and isotopic spin conservation in the nonleptonic decay of hyperons

The possibility is considered that there exists a universal V-A interaction and complete symmetry in the nonleptonic decay of hyperons. The departure from the expected symmetry that is observed in actual decays Is explained by effects caused by the mesonic structure of hyperons. In close connection with the idea of complete symmetry, a new isotopic spin is defined, which is equal to 1/2 for all baryons and to 0 or 1 for K mesons. The law of conservation of this isotopic spin holds in nonleptonic decays.