K Mesons and Hyperons their strong and weak interactions

Abstract

This article surveys our empirical knowledge of the production processes, the nuclear interactions and the decay processes of K particles and hyperons, as this appeared at the close of 1956, and interprets these phenomena within the framework of the chargeindependent classification scheme proposed by Gell-Mann and by Nishijima for these ' strange particles '. T h e assignment of a ' strangeness ' quantum number to each strongly interacting particle is a deep-lying aspect of this scheme, and the main qualitative features of the empirical data allow a direct interpretation in terms of a law of conservation of strangeness through all strong interactions. Where appropriate, more detailed analyses of the phenomena are made on the assumption that charge independence holds for these strong interactions.The evidence on decay processes for K particles and hyperons is discussed in some detail. These processes violate the strangeness conservation law and also involve changes in the total isotopic spin for those cases where this quantity is relevant for the final particles.The success of Gell-Mann's AT = 8 rule in accounting for certain aspects of the decay data is considered for each of the latter cases ; this rule is given a simple origin in Schwinger's model for strange particle decay processes, which is discussed briefly. T h e implications of symmetry between particle and antiparticle, as pointed out by Gell-Mann and Pais for c and Planck's constant fi each have the value unity. However these symbols will sometimes be retained in the formulae in order to display the dimensional character of the quantities considered.

Invariance in elementary particle physics

“…It may be that these representations will be required to explain some of the anomalous cosmic-ray events. There is some evidence (see Dalitz 1957 for a summary) for a heavy boson of mass about 1500 e.m. undergoing a cascade decay w+ -+ K' + ?TO -+ p+ + v + ?TO.…”

Hyperon Beam Physics

“…This idea was proposed by Gell-Mann (1953). By the time of the review articles by Dalitz (1957) and Gell-Mann & Rosenfeld (1957), the classification scheme for the spin-parity-1/2+ hyperons (the A, an I-spin singlet with S = -1, the L+,LO,L-, an I-spin triplet also with S= -1, and the 3°,3-I-spin doublet with S = -2) was established in notation still currently used.…”