Lectures on walking technicolor, holography and gauge/gravity dualities

TL;DR

This paper reviews walking technicolor as a strongly-coupled extension of the standard model, emphasizing the role of gauge/gravity dualities as non-perturbative tools, with illustrative examples from holography.

Contribution

It provides a pedagogical overview of walking technicolor and demonstrates the application of gauge/gravity dualities through specific holographic models.

Findings

Walking technicolor can produce realistic electroweak symmetry breaking.

Gauge/gravity dualities offer valuable non-perturbative insights into strongly-coupled theories.

Holographic models can be constructed both bottom-up and top-down for phenomenological studies.

Abstract

Dynamical electro-weak symmetry breaking is an appealing, strongly-coupled alternative to the weakly-coupled models based on an elementary scalar field developing a vacuum expectation value. In the first two sections of this set of lectures, I summarize the arguments, based on low-energy phenomenology, supporting walking technicolor as a realistic realization of this idea. This pedagogical introduction to walking technicolor, and more generally to the physics of extensions of the standard model, makes extensive use of effective field theory arguments, symmetries and counting rules. The strongly-coupled nature of the underlying interactions, and the peculiar quasi-conformal behavior of the theory, require to use non-perturbative methods in order to address many fundamental questions within this framework. The recent development of gauge/gravity dualities provides an ideal set of such non-perturbative instruments. The remaining two sections illustrate the potential of these techniques with two technical examples, one within the bottom-up phenomenological approach to holography in five-dimensions, the other within a more systematic top-down construction derived from ten-dimensional type-IIB supergravity.