Topological Reconstruction of Decays with Missing Particles

We present a new reconstruction method for decays of long-lived particles with missing particles in the final state. These undetected final state particles are reconstructed using topological information obtained from secondary vertices. Two exemplary decays Bs0→τ+τ- and Bs0→μ±τ± are studied with event samples of parametrized Monte Carlo simulation. The parametrization is based on the expected performance of general purpose LHC experiments. The secondary vertices are obtained from three-prong decays of the τ-leptons. The resulting mass resolutions (FWHM) obtained for signal decays amount to 1.1 GeV for Bs0→τ+τ- and to 0.59 GeV for Bs0→μ±τ±