Mixing stops at the LHC

TL;DR

This paper explores the phenomenology of light stop particles with large mixing in R-symmetric models and MSSM, highlighting potential decay modes, current experimental gaps, and the importance of targeted searches at the LHC.

Contribution

It identifies a novel decay channel for light stops involving flavor violation and assesses the sensitivity of existing LHC searches to this scenario.

Findings

Current LHC searches have limited sensitivity to this stop decay mode.

Shape-based hadronic SUSY searches could potentially exclude light stops in this scenario.

Flavor violating decay modes may be a blind spot in current stop searches.

Abstract

We study the phenomenology of a light stop NLSP in the presence of large mixing with either the first or the second generation. R-symmetric models provide a prime setting for this scenario, but our discussion also applies to the MSSM when a significant amount of mixing can be accommodated. In our framework the dominant stop decay is through the flavor violating mode into a light jet and the LSP in an extended region of parameter space. There are currently no limits from ATLAS and CMS in this region. We emulate shape-based hadronic SUSY searches for this topology, and find that they have potential sensitivity. If the extension of these analyses to this region is robust, we find that these searches can set strong exclusion limits on light stops. If not, then the flavor violating decay mode is challenging and may represent a blind spot in stop searches even at 13 TeV. Thus, an experimental investigation of this scenario is well motivated.