A negative S parameter from Holographic Technicolor

TL;DR

A new class of 5D models, Holographic Technicolor, is presented, which fulfills the basic requirements for a candidate of comprehensible 4D strong dynamics at the electroweak scale and is the firsttechnicolor-like model able to provide a vanishing or even negative tree-level S parameter, avoiding any no-go theorem on its sign.

Abstract

We present a new class of 5D models, Holographic Technicolor, which fulfills the basic requirements for a candidate of comprehensible 4D strong dynamics at the electroweak scale. It is the first Technicolor-like model able to provide a vanishing or even negative tree-level S parameter, avoiding any no-go theorem on its sign. The model is described in the large-N regime. S is therefore computable: possible corrections coming from boundary terms follow the 1/N suppression, and generation of fermion masses and the S parameter issue do split up. We investigate the model's 4D dual, probably walking Technicolor-like with a large anomalous dimension.

Figures (2)

• Figure 1: Masses at $\mathcal{O}\left(G^0\right)$ divided by $l_1$ for the lightest vector and axial KK modes of the $W$, as a function of the condensate in their respective channel $o_{V,A}$, for $d=2$.
• Figure 2: Value of $S_{\operatorname{tree}}/N$ ---for $d=2$ and for different values of $o_V$--- as a function of the ratio of condensates in the two channels $o_A/o_V$, and for the pure AdS case.