Meson Decay and the Theory of Nuclear Forces

Abstract

In recent observations with the photographic plate method, Lattes, Muirhead, Occhialini and Powell1 have given direct evidence of cosmic ray mesons with two different masses; furthermore, in some of their pictures the heavier meson stops in the emulsion and emits a lighter meson. At first one is tempted to identify these two mesons with the vector and pseudoscalar ones postulated in the Schwinger mixed meson theory of nuclear forces. Wentzel2 has, in fact, recently suggested that a vector meson can disintegrate into a pseudoscalar meson plus a photon, and one might conjecture whether this is not the process observed by the Bristol group1. According to calculations by Finkelstein3, this process has a lifetime of 4 × 10−18 sec. and would thus be too fast to be detected in the plate. Finkelstein's results show, in addition, that the contribution of the vector meson instability to the soft component of cosmic radiation would result from that process, that is, from photons and not from β-decay, which would then be slower by a factor of 1010.