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.
Highlights
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 ∼200–350 GeV and a lifetime between 0.1–1 mm/c together, with √a nearly degenerate dark fermion that may be probed at the 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
Summary
Due to the large number of experimental signatures and classes of long-lived massive particles, we focus only in the case where a colored electroweaksinglet scalar decays to a right-handed top quark and a dark fermion that is stable throughout the detector length. Light colored scalar particles with the quantum numbers of an up-type quark are well motivated scenarios This is the case within SUSY extensions of the Standard Model such as the Minimal Supersymmetric Standard Model (MSSM). The authors in [35] have proposed a monojet-like search optimized for the four-body decay mode of the stop with an additional bjet requirement These studies significantly complement the search efforts by the CMS [36,37] and ATLAS [38,39] collaborations to address the light-stop window regime with the full data set at center of mass energies of 8 TeV.
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