Detection of sleptons at a linear collider in models with small slepton-neutralino mass differences

A feasibility study is presented to precisely measure the masses of charged sleptons and the lightest neutralino in $e^+e^-\to\smur\smur$ and $e^+e^-\to\stau_1\stau_1$ production. Different mSUGRA scenarios with small slepton-neutralino mass differences of a few GeV are invesigated. The analysis is based on a detailed simulation of the final state lepton energy spectra including background reactions and assuming realistic experimental conditions at the TESLA $e^+e^-$ Linear Collider. Effects on the mass resolutions due to beams colliding head-on or under a crossing angle are discussed.