Search for a Strange Boson of Mass Less than 670 MeV

The cross section for the production of a strange boson in the mass region 565 to 670 MeV in the reaction $K^{-}p\to p{\kappa }^{-}$ is found to be less than 11 μb with 95% confidence. A crude theoretical estimate of the cross section based upon a simple pole model yields 11 μb.