Determining the parameters of the minimal supergravity model from2l+ETmiss+(jets)final states at CERN LHC

We analyze the events with two same-flavor, $\mathrm{o}\mathrm{p}\mathrm{p}\mathrm{o}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{e}-\mathrm{s}\mathrm{i}\mathrm{g}\mathrm{n}\mathrm{}\mathrm{leptons}{+E}_T^{\mathrm{miss}}+\left(\mathrm{jets}\right)$ as expected in $\mathrm{pp}$ collisions at the CERN LHC within the framework of the minimal supergravity model. The objective is the determination of the parameters $m_0$ and $m_{1/2}$ of this model (for a given value of $\tan \beta$). The signature $l^{+}{l}^{-}{+E}_T^{\mathrm{miss}}+\left(\mathrm{jets}\right)$ selects the leptonic decays ${\tilde{\chi }}_2^0\to {\tilde{\chi }}_1^0{l}^{+}{l}^{-},$ ${\tilde{\chi }}_2^0\to l_{L,R}^{\pm }{l}^{\mp }\to {\tilde{\chi }}_1^0{l}^{+}{l}^{-}$ of ${\tilde{\chi }}_2^0,$ produced in $\tilde{g}/\tilde{q}$ decays. We exploit the fact that the invariant dilepton mass distribution has a pronounced structure with a sharp edge at the kinematical end point even in such an inclusive final state over a significant part of parameter space. We determine the domain of parameter space where the edge is expected to be visible. We show that a measurement of this edge already constrains the model parameters 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 decays of ${\tilde{\chi }}_2^0$ and the decays into sleptons $l_{L,R}.$ This procedure may make it possible to get information on SUSY particle masses already with low luminosity, ${\mathcal{L}}_{\mathrm{int}}{=10\mathrm{}}^3{\mathrm{pb}}^{\mathrm{-}1}.$