Photoproduction of Narrow Resonances

Abstract

A very narrow resonance with a mass of 3.105 GeV/${\mathit{c}}^{2}$ is observed in the reaction $\ensuremath{\gamma}+\mathrm{Be}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}+{\ensuremath{\mu}}^{\ensuremath{-}}+X$. The total cross section for this process, as well as its $t$ distribution, is given.