On the Theory of Hyperons and Heavy Mesons

During the past few years there haa accumulated so much experimental information on hyperons and heavy mesons that some of the many puzzling questions on these strange particles arebeing resolved. Under such circumstances one is often motivated to seek for an ordering principle by which one can understand why there are such particles as being known, why they are of such nature as being observed. It is expected that the solution of this problem would be of great help to bring the present status ofthe theory of elementary particles much further. Besides such problems of a rather deep nature, we are interested in understanding the curious behaviours of the heavy unstable particles in a consistent manner and in predicting their implications to the pion-nucleon interactions. In this report we shall confine ourselves to the latter problem. The theory of hyperons and heavy mesons is closely related to the pion theory on which we base our reasoning and arguments, and we have assumed that these particles are so strongly coupled to each other that one cannot treat them separately for quantitative calculations. Also it can readily be shown through tentative estimations of the strength of the nuclear interaction of these particles that the assumption mentioned above would certainly be reasonable. Hence the theory of these strongly coupled particles is sharply contrasted to quantum electrodynamics which is practically a closed theory. Since, however, the theory of pions as it stands is not yet fully successful in explaining the nature of pions a t energies of the order of Gev, we cannot expect any quantitative theory of these particles for the time being. Still it is possible to draw some interesting conclusions on the nature of strange particlcs on which one can readily understand many of their striking behaviours observed so far. These arguments arc baaed mainly on the general invariance principles in quantum field theory, which would certainly be more reliable than the present ficld