Dilepton + Jets + MET channel: Observation and Measurement of Chi02 into Chi01 and two leptons

The observability of supersymmetric dilepton final states arising from the decay $\tilde{\chi}_{2}^{o} \rightarrow \tilde{\chi}_{1}^{o} \ell \ell $, is studied within the theoretical framework of mSUGRA using the LM1 benchmark point. The analysis is targeting at integrated luminosity of 1fb-1 and, assuming the earlier discovery of supersymmetry, is optimized for the measurement of the endpoint in the dilepton invariant mass distribution. This endpoint value can then provide a first constraint towards sparticle mass measurements. The physics background of the signal decay chain comes both from SUSY and SM processes with at least two opposite-sign same-flavor leptons and is estimated using different-flavor dilepton pairs. An unbinned maximum likelihood fit is performed on the dielectron and dimuon masses separately, and the endpoint value as well as the number of signal and background events are obtained. Systematic uncertainties on the endpoint are found to be small.