A possible means to obtain evidence concerning the spin of the K′-meson

Summary  It is shown that antiproton-proton annihilation at rest into a K′ and K′ meson can provide information about the spin of the K′ if a number of assumptions are justified. These assumptions are: 1) the K′ has spin either zero or one; 2) the annihilation occurs in anS-state; 3) the K′ and K′ decay as free particles; 4) the background of annihilation events which cannot be distinguished kinematically from K′K′ production is small. The method consists in showing that if the K′ has spin one, it is extremely unlikely that the angular distributions will be isotropic with respect to all the angles specified by the production and decay of the K′ and K′. The degree of anisotropy is not unique. However, it would require a triple coincidence for isotropy;i.e. three relationships would have to hold among the parameters specifying the interaction. If the K′ has spin zero, the angular distribution is of course isotropic. All of the assumptions are open to some question. Nevertheless, it may be possible to obtain some evidence about the spin of the K′ from the angular distributions, even if the assumptions are false.