Experimental Restrictions on Ne'eman's Fifth Interaction

Recently, Ne'eman has proposed a "fifth interaction" between the strangeness current and a neutral vector meson χ, for the purpose of breaking SU(3) symmetry. We show that a χ mass less than 2mπ would be inconsistent with a variety of experiments, including K-mesonic atoms, the long-range pp potential, K1 regeneration from a K2 beam, the Lamb shift, modern refinements of the Cavendish "ice-bucket" experiment, and the absence of π0→γ+χ and χ→e++e-. The remaining possibility, that mχ exceeds 2mπ, is discussed briefly.