Long-lived Colored Scalars at the LHC

TL;DR

This paper investigates the collider signatures of long-lived colored scalars at the LHC, identifying parameter regions consistent with current searches and proposing strategies to improve detection of such particles.

Contribution

It introduces a new analysis of long-lived colored scalars with specific mass and lifetime ranges, linking them to supersymmetric models and proposing combined cut strategies for better detection.

Findings

Identifies a parameter space with 200-350 GeV scalar mass and 0.1-1 mm/c lifetime compatible with current searches.

Proposes a combined missing transverse energy and impact parameter cut strategy to exclude new regions.

Connects the model to the light-stop window in supersymmetry, suggesting possible natural origins.

Abstract

We study the collider signatures of a long-lived massive colored scalar transforming trivially under the weak interaction and decaying within the inner sections of a detector such as ATLAS or CMS. In our study, we assume that the colored scalar couples at tree-level to a top quark and a stable fermion, possibly arising from a dark sector or from supersymmetric extensions of the Standard Model. After implementing the latest experimental searches for long-lived colored scalars, we observe a region of parameter space consistent with a colored electroweak-singlet scalar with mass between $\sim200-350$ GeV and a lifetime between $0.1-1$ $\text{mm}/c$ together, with a nearly degenerate dark fermion that may be probed at the $\sqrt{s}=13$ TeV LHC. We show that a search strategy using a combination of cuts on missing transverse energy and impact parameters can exclude regions of parameter space not accessed by prompt searches. We show that a region of parameter space within our simplified model may naturally arise from the light-stop window regime of supersymmetric extensions of the Standard Model, where a light mostly right-handed stop has a mass slightly larger than the lightest neutralino and decays through a four-body process.