The S-parameter in Holographic Technicolor Models
arXiv:0704.1821 · doi:10.1088/1126-6708/2007/12/003
Abstract
We study the S parameter, considering especially its sign, in models of electroweak symmetry breaking (EWSB) in extra dimensions, with fermions localized near the UV brane. Such models are conjectured to be dual to 4D strong dynamics triggering EWSB. The motivation for such a study is that a negative value of S can significantly ameliorate the constraints from electroweak precision data on these models, allowing lower mass scales (TeV or below) for the new particles and leading to easier discovery at the LHC. We first extend an earlier proof of S>0 for EWSB by boundary conditions in arbitrary metric to the case of general kinetic functions for the gauge fields or arbitrary kinetic mixing. We then consider EWSB in the bulk by a Higgs VEV showing that S is positive for arbitrary metric and Higgs profile, assuming that the effects from higher-dimensional operators in the 5D theory are sub-leading and can therefore be neglected. For the specific case of AdS_5 with a power law Higgs profile, we also show that S ~ + O(1), including effects of possible kinetic mixing from higher-dimensional operator (of NDA size) in the theory. Therefore, our work strongly suggests that S is positive in calculable models in extra dimensions.
21 pages, 2 figures. v2: references added
References in corpus (3)
Cited by in corpus (10)
- Minimal Walking Technicolor: Set Up for Collider Physics
- Electroweak Breaking on a Soft Wall
- The Soft-Wall Standard Model
- Describing viable technicolor scenarios
- Benchmarks for new strong interactions at the LHC
- Holographic technicolor models and their S-parameter
- Technicolor Signals at the LHC
- Further Study of an Approach to the Unification of Gauge Symmetries in Theories with Dynamical Symmetry Breaking
- A Four-site Higgsless Model with Wavefunction Mixing
- A linear moose model with pairs of degenerate gauge boson triplets