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Relative Parity of Charged and Neutral K-Particles

  • Pais, A.
Publication Date
Oct 15, 1958
DOI: 10.1103/PhysRev.112.624
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Neither from the experimental nor from a theoretical point of view is it obvious that the relative parity p(K) of charged and neutral K-particles is even. This paper is devoted to a study of the case of odd p(K). It is shown (Sec. II) that in the approximation δ≡(MΣ−MΛ)MΛ=0 the π-nucleon phenomena are charge independent provided certain coupling-constant relations are satisfied. The strong Λ-neutron and Λ-proton forces are no longer equal, but if π-interaction between Λ and nucleon predominates this equality is still nearly true. Σ- and K-mass differences may occur which are not mediated by the electromagnetic field. The effects of finite δ on π-nucleon charge independence deviations are explored in Sec. III. Charge symmetry is also violated. These deviations appear not to be disturbing. It is shown that the possibility exists of a negative contribution of a new kind to the proton-neutron mass difference. π-baryon and K-baryon couplings alone would lead to contradictions with experiment. These can be overcome by introducing a KKπ-coupling; for odd p(K) this is compatible with parity conservation (Sec. IV). A qualitative explanation of K-exchange scattering is given which is not unsatisfactory. The consequences for elastic K-scattering are discussed. For ΣK-production in π-nucleon collisions the possibility exists of a violation of the triangle inequalities. There appears to be a good promise for understanding the forward (backward) peaking of charged (neutral) hyperons in associated production. It is pointed out that the K-pair effects due to KKπ-interaction lead to further violations of charge independence. The main effect anticipated is for π-nucleon S-scattering. The influence of a lack of charge symmetry on the nucleon-charge distribution is commented on. Section V deals with the symmetries of the strong interactions classified in terms of the four-dimensional real orthogonal group. Full four-invariance is broken by parity. It is conjectured that each symmetry class is characterized by one universal coupling constant. In Sec. VI the main points of direct experimental interest are summarized.

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