Measurement of Masses in SUGRA Models at LHC

This note presents new measurements at ``Point 5'' in the minimal SUGRA model with $m_0=100\,\GeV$, $\mhalf=300\,\GeV$, $A_0=0$, $\tan\beta=2$, and $\sgn\mu=+$ based on four-body distributions from three-step decays and on minimum masses in such decays. These measurements allow masses to be determined without relying on a model. This note also contains an estimate of the possible statistical errors on the dilepton endpoint. Slepton universality can be tested at the $\sim0.1\%$ level at high luminosity. In addition the effect of enlarging the parameter space of the minimal SUGRA model is discussed. The direct production of left handed sleptons and the non-observation of additional structure in the dilepton invariant mass distributions is shown to produce powerful additional constraints.