Mono-b events from single stop production at the HL-LHC and HE-LHC

TL;DR

This paper explores the potential to detect single stop production via mono-b events at future high-energy colliders, providing a new approach to confirm the existence of top-squarks in supersymmetry.

Contribution

It investigates the observability of mono-b signatures from single stop production at HL-LHC and HE-LHC, highlighting their potential to probe stop and higgsino masses up to 1.6 TeV and 550 GeV.

Findings

Stop mass can be probed up to 1.6 TeV at HE-LHC.

Higgsino mass can be probed up to 550 GeV at HE-LHC.

Exclusion limits for stop mass are established for HL-LHC and HE-LHC.

Abstract

Top-squarks (stop) play an important role in SUSY naturalness. The stop pair production is considered as the most effective way to search for stop at the LHC. However, the collider signature of stop pair production is usually characterized by $t\bar{t}$ plus missing transverse energy, which is also predicted in many other non-supersymmetric models. On the other hand, the single stop production via the electroweak interaction can provide some distinctive signatures, and thus will help to confirm the existence of the stop. In this paper, we investigate the observability of the mono-$b$ events from the single stop production process $pp \to \tilde t_1 \tilde{\chi}^-_1 \to b+ E\!\!\!\!/_T$ in a simplified MSSM framework where the higgsinos and stops are the only sparticles at the HL-LHC and HE-LHC. We find that the stop mass and the higgsino mass may be probed up to about 1.6 TeV and 550 GeV at $5\sigma$ level at the HE-LHC with the integrated luminosity ${\cal L} = 15~\text{ab}^{-1}$. We also present the $2\sigma$ exclusion limits of the stop mass at the HL-LHC and HE-LHC.