Hidden Dark Sectors: Jet Substructure and Effective Field Theories
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Date
2022-10-04
Authors
Doss, Joel
Journal Title
Journal ISSN
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Publisher
University of Oregon
Abstract
The search for physics beyond the Standard Model is a daunting task. As parameter spaces for compelling models shrink, there is motivation for more radical concepts. However, there is a need for understanding the structure of novel signal regions. We describe two analyses on extensions to the Standard Model wherein the dynamics of new particles are isolated.
We first examine collider predictions for a dark sector with QCD-like properties. Pair production of dark quarks can result in a wide variety of signatures. A challenging signal results when production induces a parton shower with a high multiplicity of collimated dark hadrons, which subsequently decays to Standard Model hadrons. The final states contain jets whose substructure encodes their non-QCD origin. This is a subtle signature of strongly coupled beyond the Standard Model dynamics whose analyses must incorporate systematic errors from model approximations. We estimate theoretical uncertainties for a substructure observable designed to be sensitive to the gauge structure of the underlying object, the two-point energy correlator. We explore the separability against the QCD background as model parameters are varied. Estimates are provided that quantify one's ability to distinguish these dark sector jets from the overwhelming QCD background.
Next, we look at Effective Field Theory (EFT) extensions of the Standard Model. EFTs are systematically improvable expansions suppressed by a new physics scale M. For EFT predictions in parameter spaces where M is less than the center-of-mass energy, concerns of self-consistency emerge, which can manifest as a violation of perturbative partial-wave unitarity. However, when searching for EFT effects at a hadron collider using an inclusive strategy, we typically do not have access to the event-by-event value of the partonic center-of-mass energy. This motivates the need for a formalism that incorporates parton distribution functions into the perturbative partial-wave unitarity analysis. Our approach opens up a potentially valid region of the EFT parameter space where M is much less than the center-of-mass energy of the collider. The perturbative unitarity bounds are sensitive to the details of a given search, an effect we investigate by varying kinematic cuts.
This dissertation consists of previously published co-authored material.
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Keywords
Beyond Standard Model Physics, Collider Physics, Dark Matter, Effective Field Theories, Strongly Coupled Dynamics