Leptonic mono-top from single stop production at LHC

TL;DR

This paper explores the potential to detect single stop production via leptonic mono-top signatures at the 14 TeV LHC, proposing a new observable to reduce background and estimating the discovery reach.

Contribution

It introduces a novel lab-frame observable, $ ext{cos} heta_{b ext{l}}$, to enhance mono-top signal detection in compressed electroweakino scenarios at the LHC.

Findings

Single stop production can be probed at 2σ level at HL-LHC for certain mass ranges.

The proposed observable effectively reduces SM backgrounds in mono-top searches.

Discovery potential extends up to 760 GeV for stop mass and 150 GeV for neutralino mass.

Abstract

Top squark (stop) can be produced via QCD interaction but also the electroweak interaction at the LHC. In this paper, we investigate the observability of the associated production of stop and chargino, $pp \to \tilde{t}_1\tilde{\chi}^-_1$, in compressed electroweakino scenario at the 14 TeV LHC. Due to the small mass-splitting between the lightest neutralino ($\tilde{\chi}^0_1$) and chargino ($\tilde{\chi}^-_1$), such a single stop production can give a mono-top signature through the stop decay $\tilde{t}_1 \to t \tilde{\chi}^0_1$. Focusing on the leptonic mono-top channel, we propose a lab-frame observable $\cos\theta_{b\ell}$ to reduce the SM backgrounds in virtue of a boosted top quark from the stop decay. We find that the single stop production can be probed at $2\sigma$ level at the HL-LHC for $m_{\tilde{t}_1}<760$ GeV and $m_{\tilde{\chi}^0_1}<150$ GeV.