Electroweak symmetry breaking from gauge/gravity duality

We use the gauge/gravity duality to study a model of walking technicolor. The latter is a phenomenologically promising framework for dynamical electroweak symmetry breaking. A traditional problem for technicolor models has been the need to address gauge theories at strong coupling. Recent developments in gauge/gravity duality provide a powerful tool for handling this problem. First, we revisit previously considered holographic models of QCD-like technicolor from D-branes. In particular, we develop analytical understanding of earlier numerical computations of the Peskin-Takeuchi S-parameter. Then we apply this method to the investigation of a model of walking technicolor, obtained by embedding D7-D7¯ probe branes in a recently discovered type IIB background dual to walking behaviour. As a necessary step, we also show that there is an embedding of the techniflavor branes, that realizes chiral symmetry breaking. Finally, we show that the divergences that appear in the S-parameter can be removed by using holographic renormalization.