Search for Bound States of theηMeson in Light Nuclei

Abstract

A search for nuclear-bound states of the $\eta$ meson has been carried out. Targets of lithium, carbon, oxygen, and aluminum were placed in a ${\pi }^{+}$ beam at 800 MeV/c. A predicted $\eta$ bound state in ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}_{}^{*}{}_{}{}^{}\left(E_x\approx 540 \mathrm{MeV}\right)$ with a width of ≅ 9 MeV was not observed. A bound state of a size ⅓ of the predicted cross section would have been seen in this experiment at a confidence level of $3\sigma \mathrm{}(P>\mathrm{}0.9987\mathrm{})\mathrm{}$.