Measurement of the ${\gamma }^{\star }{\gamma }^{\star }\to {\eta }^{\mathrm{\prime }}$ transition form factor

We study the process $e^{+}{e}^{-}\to e^{+}{e}^{-}{\eta }^{\mathrm{\prime }}$ in the double-tag mode and measure for the first time the ${\gamma }^{\star }{\gamma }^{\star }\to {\eta }^{\mathrm{\prime }}$ transition form factor $F_{{\eta }^{\mathrm{\prime }}}(Q_1^2,Q_2^2)$ in the momentum-transfer range \mbox{2 $<Q_1^2,Q_2^2<$ 60 GeV${}^2$}. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb${}^{-1}$ collected at the PEP-II $e^{+}{e}^{-}$ collider with the BaBar detector at center-of-mass energies near 10.6 GeV.