Experimental search for a new light baryon

A search was conducted for a light baryon $X^{++}$ in the mass range $M_N+M_{\pi }\ge M_X\ge M_N$, by bombarding a ${\mathrm{CH}}_2$ target with 460 MeV protons, and detecting the products in the Medium Resolution Spectrometer, which was placed at a scattering angle of 15 degrees. No doubly charged baryon in this mass range was detected, thus setting an upper limit of a few tens pb/sr for the reaction. The experiment indicates that if such a light baryon exists its interaction with the "ordinary" physical world is very weak, probably at least ${10}^7$ times weaker than the strong interaction.