Precision Calculation for Supersymmetric Particle Decays

TL;DR

This paper calculates one-loop corrections to neutralino decays in the MSSM, revealing significant changes in decay rates and invariant mass distributions crucial for supersymmetric particle mass reconstruction.

Contribution

It provides the first detailed one-loop analysis of neutralino leptonic decays, including three-body decay scenarios and their impact on observable distributions.

Findings

One-loop corrections significantly increase leptonic decay branching ratios.

Hard photon emission alters the dilepton invariant mass distribution shape.

Results improve accuracy of supersymmetric particle mass measurements.

Abstract

In the Minimal Supersymmetric Standard Model with conserved R-parity, the decays of the next-to-lightest neutralino into the lightest neutralino and two leptons are always involved in each supersymmetric particle decay chain. In this thesis we calculate one-loop corrections to the two-body decays of the next-to-lightest neutralino into a lepton and a slepton, which again decays into another lepton and the lightest neutralino. We also investigate a scenario where the next-to-lightest neutralino can undergo three-body decays. Not only the branching ratios of leptonic decay modes, but also the dilepton invariant mass distribution, are studied. Its endpoint is often used to reconstruct mass-differences of supersymmetric particles. At one-loop level the branching ratios of these leptonic decays are increased significantly and the shape of dilepton invariant mass distribution is altered by the hard photon emission.