Experimental consequences of no-scale supergravity in light of the CDF $ee\gamma \gamma$ event

Abstract

We explore two possible interpretations for the CDF $ee\gamma \gamma +E_T/$ event in the context of a recently proposed one-parameter no-scale supergravity model with a light gravitino. We delineate the region in parameter space consistent with the kinematics of the event interpreted either as selectron pair-production ($p\bar{p}\to {\tilde{e}}^{+}{\tilde{e}}^{-}X$, $\tilde{e}={\tilde{e}}_R,{\tilde{e}}_L$) or as chargino pair-production ($p\bar{p}\to {\chi }_1^{+}{\chi }_1^{-}X$). In the context of this model, the selectron interpretation requires $\tilde{e}={\tilde{e}}_R$ and predicts comparable rates for ${\ell }^{\pm }\gamma \gamma +E_T/$, whereas the chargino interpretation predicts comparable rates for $({\ell }^{\pm }{\ell }^{{}^{\prime }+}{\ell }^{{}^{\prime }-},{\ell }^{+}{\ell }^{-},{\ell }^{+}{\ell }^{-}jj)\gamma \gamma +E_T/$. We also consider the constraints from LEP~1.5 and the expectations for LEP~2. We point out that one of the acoplanar photon pairs observed by the OPAL collaboration at LEP~1.5 may be attributable to supersymmetry in the present model via $e^{+}{e}^{-}\to {\chi }_1^0{\chi }_1^0\to \gamma \gamma +E_T/$. We also show how similar future events at LEP~2 may be used to deduce the neutralino mass.

Comments: 36 pages, LaTeX, 19 figures (included)