Sparticle Production in Electron-Photon Collisions

Abstract

We explore the potential of electron-photon colliders to measure fundamental supersymmetry parameters via the processes $e\gamma \to \tilde{e}{\tilde{\chi }}^0$ (selectron-neutralino) and $e\gamma \to \tilde{\nu }{\tilde{\chi }}^{-}$ (sneutrino-chargino). Given the ${\tilde{\chi }}^0$ and ${\tilde{\chi }}^{-}$ masses from $e^{+}{e}^{-}$ and hadron collider studies, cross section ratios $\sigma ({\gamma }_{-})/\sigma ({\gamma }_{+})$ for opposite photon helicities determine the ${\tilde{\nu }}_L$, ${\tilde{e}}_L$ and ${\tilde{e}}_R$ masses, independent of the sparticle branching fractions. The difference $m_{{\tilde{\nu }}_L}^2-m_{{\tilde{e}}_L}^2$ measures $M_W^2\cos 2\beta$ 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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