Measuring mass and cross section parameters at a Focus Point Region

The purpose of this study is to determine the experimental uncertainties in measuring mass and cross section parameters of SUSY particles at a 500 GeV Linear Collider. In this study SUSY is a point in the focus point region of mSUGRA parameter space that is compatible with WMAP constraints on dark matter relic density. At this study point the masses of the squarks and sleptons are very heavy, and the only SUSY particles accessible at the Linear Collider would be the three lightest neutralinos, and the two lightest charginos: χ̄⁰₁, χ̄⁰₂, χ̄⁰₃, χ̄⁺₁, χ̄⁺₂, where χ̄⁰₁ is the lightest supersymmetric particle (LSP). The charginos or neutralinos may be pair produced, and the subsequent decay cascades to the LSP allow us to measure the SUSY couplings and mass spectrum. We find that by looking for the signature 2 jets plus 2 leptons plus missing energy we can determine the mass of the LSP to within 1 GeV uncertainty and that the mass differences of χ̄⁰₂ and χ̄⁰₃ with the LSP mass can be determined to better than 0.5 GeV.