Opening up the compressed region of stop searches at 13 TeV LHC

TL;DR

This paper introduces a novel method to detect light top superpartners in compressed regions at the 13 TeV LHC, using a new observable that peaks in this challenging parameter space, extending the search reach.

Contribution

The paper proposes a new observable, $R_M$, and a search strategy to improve sensitivity to compressed stop-neutralino mass regions at the LHC.

Findings

The $R_M$ distribution peaks in the compressed region, correlating with stop mass.

The method extends the stop mass reach to about 800 GeV at 13 TeV LHC with 3000 fb$^{-1}$.

The approach enhances detection prospects for compressed supersymmetric scenarios.

Abstract

Light top superpartners play a key role in stabilizing the electroweak scale in supersymmetric theories. For $R$-parity conserved supersymmetric models, traditional searches are not sensitive to the compressed regions. In this paper, we propose a new method targeting this region, with stop and neutralino mass splitting ranging from $m_{\tilde t} - m_\chi \gtrsim m_t$ to about 20 GeV. In particular, we focus on the signal process in which a pair of stops are produced in association with a hard jet, and define a new observable $R_M$ whose distribution has a peak in this compressed region. The position of the peak is closely correlated with $m_{\tilde t}$. We show that for 13 TeV LHC with a luminosity of 3000 fb$^{-1}$, this analysis can extend the reach of stop in the compressed region to $m_{\tilde t}$ around 800 GeV.