Search for Sub-threshold Photoproduction of J/ψ Mesons

A search was made for sub-threshold J/{psi} production from a carbon target by using a mixed real and quasireal Bremsstrahlung photon beam with an endpoint energy of 5.76 GeV. No events were observed, which is consistent with predictions under the assumption of quasifree production. The results place limits on exotic mechanisms that strongly enhance quasifree production.