Walking technicolor in the LHC era and beyond

Abstract

In this thesis we explore the compelling BSM model of Walking Technicolor, where new strong dynamics with a modified slowly running (walking) coupling dynamically break electroweak symmetry. We detail the Next-to-Minimal Walking Technicolor (NMWT) model, connecting an effective chiral Lagrangian to the underlying dynamics via the Weinberg Sum Rules. We discuss the theoretical upper limit on the NMWT scale, MA, set by the requirement of walking dynamics, and experimental limits from reducing tension with Electroweak Precision Data.
We investigate the potential of the Large Hadron Collider (LHC) to prob ethe NMWT model at LHC@13TeV, 36fb^-1, using dilepton signatures from heavy neutral Z0 and Z00 resonances predicted by the model. We establish a new limit in the (MA; ~g) plane, demonstrating the complementarity of the two resonances. We find the most conservative limit as MA > 3TeV for low ~g. We set the first complementary limits from searches in the Drell-Yan produced V V=V h channels, demonstrating new potential to probe the intermediate-high ~g regime.
We use a holographic model to explore WTC from a top-down approach with varying number of techniquark colours and flavours (Nc,Nf ), tuning the gauge running dynamics to produce a light Higgs and low S parameter. The resulting models predict technimeson masses and couplings above the current LHC limits, where the top-down equivalent model to NMWT lies atMA ' 4TeV, ~g ' 8. This estimate provides a benchmark for the challenge of exclusion/discovery of new strong dynamics at future collider experiments.
We begin the task of determining the future of Walking Technicolor, developing a procedure for setting expected 95% CL limits on neutral resonances in the DY dilepton channel. We use this to predict the exclusions on the NMWT parameter space for the LHC era up to HLLHC@14TeV, 3ab^-1, and for future 27TeV and 100TeV colliders. The DY dilepton channel is limited by the systematics, but can begin to probe the most extreme (large number of techni-doublets) top-down models from holography. We draw prospects on predicting limits from V V=V h searches from Drell-Yan and Vector Boson Fusion production, and to ultimately determine the fate of Walking Technicolor in the LHC era and beyond.

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ORCID for Mark Sullivan: orcid.org/0000-0001-9053-4820

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