Resonance production by two-photon interactions at SPEAR

Two-photon interactions have been studied with the SLAC-LBL Mark II magnetic detector at SPEAR. The cross section for ${\eta }^{\prime }$ production by the reaction $e^{+}{e}^{-}\to e^{+}{e}^{-}{\eta }^{\prime }$ has been measured at beam energies from 2.0 to 3.7 GeV. The radiative width ${\Gamma }_{\gamma \gamma }\left({\eta }^{\prime }\right)$ has been determined to be 5.8±1.1 keV (±20% systematic uncertainty). Upper limits on the radiative widths of the $f\left(1270\right)\mathrm{}$, $A_2\mathrm{}\left(1310\right)\mathrm{}$, and $f^{\prime }\mathrm{}\left(1515\right)\mathrm{}$ tensor mesons have been determined. A search has been made for production of the $E\left(1420\right)\mathrm{}$ by $\gamma \gamma$ collisions, but no signal is observed.