Determining the parameters of the minimal supergravity model from2l+ETmiss+(jets)final …

We analyse the events with two same-flavour, opposite-sign leptons +$E_T^{miss}$ + (jets) as expected in pp collisions at LHC within the frameworkof the minimal Supergravity Model. The objective is the determination of theparameters m_0 and m_{1/2} of this model (for a given value of $\tan\beta$).The signature $l^+ l^- + E_T^{miss}$ + (jets) selects the leptonic decays of$\tilde{\chi}^0_2$, $\tilde{\chi}^0_2 \to \tilde{\chi}^0_1 l^+ l^- $,$\tilde{\chi}^0_2 \to \tilde{l}_{L,R}^{\pm} l^{\mp} \to \tilde{\chi}^0_1 l^+l^-$. We exploit the fact that the invariant dilepton mass distribution has apronounced structure with a sharp edge at the kinematical endpoint even in suchan inclusive final state over a significant part of parameter space. Wedetermine the domain of parameter space where the edge is expected to bevisible. We show that a measurement of this edge already constrains the modelparameters essentially to three lines in the ($m_0, m_{1/2}$) parameter plane.We work out a strategy to discriminate between the three-body leptonic decaysof $\tilde{\chi}^0_2$ and the decays into sleptons $\tilde{l}_{L,R}$. Thisprocedure may make it possible to get information on SUSY particle massesalready with low luminosity, L_{int}=10^3 pb^{-1}.Comment: 30 page latex file including 19 PCX figure