Exploring the nearly degenerate stop region with sbottom decays

TL;DR

This paper explores novel LHC search strategies for nearly degenerate stop particles via sbottom decays, potentially excluding stops up to 500-600 GeV and improving sensitivity to the stop-bino coannihilation dark matter region.

Contribution

It proposes new search channels involving sbottom decays to detect nearly degenerate stops, enhancing current collider search capabilities.

Findings

Stops up to 500-600 GeV can be excluded with 13 TeV LHC data.

The proposed channels are complementary to existing SUSY searches.

Reinterpretation of existing searches already shows sensitivity.

Abstract

A light stop with mass almost degenerate with the lightest neutralino has important connections with both naturalness and dark matter relic abundance. This region is also very hard to probe at colliders. In this paper, we demonstrate the potential of searching for such stop particles at the LHC from sbottom decays, focusing on two channels with final states $2\ell+E^{\rm miss}_{\rm T}$ and $1b1\ell+E^{\rm miss}_{\rm T}$. We found that, if the lightest sbottom has mass around or below 1 TeV and has a significant branching ratio to decay to stop and $W$ ($\tilde{b} \to \tilde{t}\,W$), a stop almost degenerate with neutralino can be excluded up to about 500-600 GeV at the 13 TeV LHC with $300\,{\rm fb}^{-1}$ data. The searches we propose are complementary to other SUSY searches at the LHC and could have the best sensitivity to the stop-bino coannihilation region. Since they involve final states which have already been used in LHC searches, a reinterpretation of the search results already has sensitivity. Further optimization could deliver the full potential of these channels.