Decays of the Lightest Top Squark

TL;DR

This paper studies the decay modes of the lightest top squark in the MSSM, showing that four-body decays can dominate over two-body decays in certain mass ranges, impacting experimental search strategies.

Contribution

It identifies the dominance of four-body decay modes of the top squark over loop-induced decays in specific MSSM parameter regions, which was not previously emphasized.

Findings

Four-body decay can dominate over two-body decay in certain MSSM scenarios.

The decay mode $ ilde{t}_1 o b ilde{ au}_1 u$ is significant.

Implications for experimental searches of top squarks.

Abstract

We analyze higher order decay modes of the lightest top squark $\tilde{t}_1$ in the Minimal Supersymmetric extension of the Standard Model (MSSM), where the lightest SUSY particle (LSP) is assumed to be the neutralino $\chi_1^0$. For small $\tilde{t}_1$ masses accessible at LEP2 and the Tevatron, we show that the four-body decay mode into the LSP, a bottom quark and two massless fermions, $\tilde{t}_1 \ra b \chi_1^0 f\bar{f}'$, can dominate in a wide range of the MSSM parameter space over the loop-induced decay into a charm quark and the LSP, $\tilde{t}_1 \ra c \chi_1^0$. This result might affect the experimental searches on this particle, since only the later signal has been considered so far.