Very Light Scalar Top Quarks at the LHC

TL;DR

This paper investigates the properties, decay channels, and experimental constraints of a very light scalar top quark (stop) at the LHC, focusing on naturalness, baryogenesis, and the impact of various decay modes on detection prospects.

Contribution

It provides a comprehensive analysis of the decay modes, branching ratios, and LHC search sensitivities for a light stop, including both direct and indirect constraints.

Findings

Light stop decays via three-body, four-body, or flavour violating channels.

Existing LHC searches have varying sensitivities to these decay modes.

Constraints on light stops depend on mass and decay channel configurations.

Abstract

A very light scalar top (stop) superpartner is motivated by naturalness and electroweak baryogenesis. When the mass of the stop is less than the sum of the masses of the top quark and the lightest neutralino superpartner, as well as the of the masses of the lightest chargino and the bottom quark, the dominant decay channels of the stop will be three-body, four-body, or flavour violating. In this work, we investigate the direct and indirect constraints on a light stop, we compute the relative decay branching fractions to these channels, and we study the sensitivity of existing LHC searches to each of them.