Production of $\eta$ Mesons Near Threshold

Abstract

It is argued that the strong energy dependence of the $pd\to {}^{3}He\eta$ cross section near threshold is due to a final state interaction between the $\eta$ meson and the ${}^3$He nucleus. The large scattering length that this implies is in accord with optical potential predictions and is evidence for a nearby virtual ``bound'' state in the ${\eta }^3$He system. This model suggests that sharp structures should also be seen close to production thresholds on other light nuclei.

Comments: (Talk given at the BNL workshop on future directions in particle and nuclear physics at multi-GeV hadron beam facilities, March 4--6, 1993) 5 pages (LATEX), 4 figures (not included, available in postscript form from the author on DECNET 19823::CW), UCL-HEP-9302