Inner Symmetry in Baryon Structures and Leptonic Decays

Under the assumption that the baryon is composed of three subnuclear particles in a nonrelativistic bound state analogous to the nuclear structure, the possible inner symmetries of the baryon structure are discussed by comparing with some characteristic features of the leptonic decays, such as n</it> → p</it> and Λ→ p</it>. First, under the charge independence, the characteristic parameters of the neutronβ decay are expressed in terms of the nucleon structure constants. By comparing the parameters with experiments, it is concluded that the totally symmetric spin-unitary spin part is dominant in the nucleon structure. This is true in the baryon structures in the SU</it><inf>3</inf> symmetric case. Under the SU</it><inf>3</inf> invariance, the following relation between theβ decays of neutron and Λ particle is also derived: (G</it><inf>A</inf>/G</it><inf>V</inf>)<inf>Λ→ p</it></inf> = (1/2) × (G</it><inf>A</inf>/G</it><inf>V</inf>)<inf>n</it> → p</it></inf> -1/6 ≃ -0.76, where (G</it><inf>A</inf>/G</it><inf>V</inf>)<inf>n</it> → p</it></inf> ≃ -1.185 is used. The broken SU</it><inf>3</inf> symmetry is estimated by making use of the existing experiments on theβ decay of Λ particle. Finally the decay rates for various leptonic decays are obtained from the theoretical values, F</it> ≃ 0.55 and D</it> ≃ 0.65, determined by the experimental value of (G</it><inf>A</inf>/G</it><inf>V</inf>)<inf>n</it> → p</it></inf> in the SU</it><inf>3</inf> symmetry case of the present theory. The results are consistent with the experiments.