Sparticle Production in Electron-Photon Collisions

Abstract

We explore the potential of electron-photon colliders to measure fundamental supersymmetry parameters via the processes $e{\hat{I}}^3\to \tilde{e}\tilde{\ddot{I}}{‡}^0$ (selectron-neutralino) and $e{\hat{I}}^3\to \tilde{\hat{I}}½\tilde{\ddot{I}}{‡}^{-}$ (sneutrino-chargino). Given the $\tilde{\ddot{I}}{‡}^0$ and $\tilde{\ddot{I}}{‡}^{-}$ masses from $e^{+}{e}^{-}$ and hadron collider studies, cross section ratios $\ddot{I}ƒ({\hat{I}}_{-}^3)/\ddot{I}ƒ({\hat{I}}_{+}^3)$ for opposite photon helicities determine the $\tilde{\hat{I}}{½}_L$, ${\tilde{e}}_L$ and ${\tilde{e}}_R$ masses, independent of the sparticle branching fractions. The difference $m_{\tilde{\hat{I}}{½}_L}^2-m_{{\tilde{e}}_L}^2$ measures $M_W^2\cos 2{\hat{I}}^2$ in a model-independent way. The ${\tilde{e}}_L$ and ${\tilde{e}}_R$ masses test the universality of soft supersymmetry breaking scalar masses. The cross section normalizations provide information about the gaugino mixing parameters.

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