Mass determination method for the left and right selectron above production threshold

The determination of the masses of supersymmetric particles, such as the selectron, for energies above threshold using the energy end-point method is subject to signal deconvolution difficulties and to standard model and supersymmetry backgrounds. The important features of $e_{R,L}^{\pm }$ production are used to design an experimentally robust method, with good resolution, both for determining the $e_{R,L}$ and the ${\tilde{\chi }}_1^0$ masses and for suppressing backgrounds. Additional features, such as the determination of the relative leptonic branching ratios of the selectron are present in the method.