Determination of supersymmetric masses using kinematic fits at the LHC

TL;DR

This paper introduces a novel method combining mass scans, kinematic fitting, and angular decay analysis to reconstruct SUSY particle masses at the LHC, even amidst complex backgrounds and experimental uncertainties.

Contribution

It presents a new approach integrating genetic algorithms and decay information to determine SUSY masses from LHC data with improved accuracy.

Findings

Method can derive probability maps of SUSY parameter space.

Effective in fully hadronic decay modes with background suppression.

Accounts for experimental resolutions and combinatorial backgrounds.

Abstract

In case of the discovery of supersymmetry at the LHC, the goal will be to identify the underlying theory, its fundamental parameters, and the masses of SUSY particles. We followed here the approach to reconstruct the decay chains in SUSY events under the assumption of common intermediate masses. These masses cannot be extracted from each event because of the unmeasured LSP momenta in case of R-parity conservation. But an ensemble of events can be over-constrained, if the decay chains are long enough, such that enough mass constraints are available. Here, we present a new method combining a) a SUSY mass scan, b) a kinematic fitting based on a genetic algorithm for decay chain reconstruction, and c) the usage of angular decay information to suppress the background from other SUSY processes. Taking into account the full combinatorial background and experimental resolutions in the most difficult case of the fully hadronic decay mode, we demonstrate, within one SUSY scenario, that this method can be used to derive a probability map of the SUSY parameter space.