Single top squark production as a probe of natural supersymmetry at the LHC

TL;DR

This paper investigates single top squark production at the LHC as a novel way to probe natural supersymmetry, focusing on specific signatures and their sensitivity at high luminosity.

Contribution

It introduces the analysis of electroweak single stop production and compares its sensitivity to traditional methods in natural SUSY scenarios.

Findings

The b+ missing energy signature offers better sensitivity than the monotop signature.

Parameter space with higgsino mass 100-225 GeV and stop mass up to 620 GeV can be probed.

Single stop production can achieve significant detection prospects at the 14 TeV HL-LHC.

Abstract

Light top squarks (stops) and light higgsinos are the key features of natural SUSY, where the higgsinos $\tilde{\chi}^{\pm}_{1}$ and $\tilde{\chi}^0_{1,2}$ are nearly degenerate and act as the missing transverse energy ($E^{miss}_T$) at the LHC. Besides the strong production, the stop can be produced via the electroweak interaction. The determination of the electroweak properties of the stop is an essential task for the LHC and future colliders. So in this paper, we investigate the single stop ($\tilde{t}_1$) production $pp \to \tilde{t}_1+ E^{miss}_T$ in the natural SUSY at the LHC, which gives the monotop signature $t+ E^{miss}_T$ from $\tilde{t}_1\to t \tilde{\chi}^0_{1,2}$ or the monobottom signature $b+ E^{miss}_T$ from $\tilde{t}_1 \to b \tilde{\chi}^+_{1}$. We perform Monte Carlo simulations for these signatures and obtain the results: (1) The signal $b+ E^{miss}_T$ has a better sensitivity than $t+ E^{miss}_T$ for probing natural SUSY; (2) The parameter region with a higgsino mass 100 GeV$\lesssim \mu \lesssim$ 225 GeV and stop mass $m_{\tilde{t}_1} \lesssim$ 620 GeV, can be probed through the single stop production with $S/\sqrt{B} > 3$ and $4\% \lesssim S/B \lesssim19\%$ at 14 TeV HL-LHC with an integrated luminosity of 3000 fb$^{-1}$.