Decays of the Lightest Top Squark

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, ${\tilde{t}}_1\text{ra}b{\chi }_1^{0}f{\bar{f}}^{\prime }$, can dominate in a wide range of the MSSM parameter space over the loop-induced decay into a charm quark and the LSP, ${\tilde{t}}_1\text{ra}c{\chi }_1^0$. This result might affect the experimental searches on this particle, since only the later signal has been considered so far.

Comments: 21 pages with 4 figures, Latex. Typo corrected and references updated. To appear in Phys. Rev. D