Christophe Grojean

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We present a 5D gauge theory in warped space based on a bulk SU(2)L x SU(2)R x U(1)(B-L) gauge group where the gauge symmetry is broken by boundary conditions. The symmetry breaking pattern and the mass spectrum resemble that in the standard model (SM). To leading order in the warp factor the rho parameter and the coupling of the Z (S parameter) are as in(More)
We consider extra dimensional gauge theories on an interval. We first review the derivation of the consistent boundary conditions (BC’s) from the action principle. These BC’s include choices that give rise to breaking of the gauge symmetries. The boundary conditions could be chosen to coincide with those commonly applied in orbifold theories, but there are(More)
We consider various constraints on Higgsless models of electroweak symmetry breaking based on a bulk SU(2)L×SU(2)R×U(1)B−L gauge group in warped space. First we show that the S parameter which is positive if fermions are localized on the Planck brane can be lowered (or made vanishing) by changing the localization of the light fermions. If the wave function(More)
We develop a simple description of models where electroweak symmetry breaking is triggered by a light composite Higgs, which emerges from a strongly-interacting sector as a pseudo-Goldstone boson. Two parameters broadly characterize these models: mρ, the mass scale of the new resonances and gρ, their coupling. An effective low-energy Lagrangian approach(More)
We calculate the tree-level oblique corrections to electroweak precision observables generated in higgless models of electroweak symmetry breaking with a 5D SU(2)L×SU(2)R ×U(1)B−L gauge group on a warped background. In the absence of brane induced kinetic terms (and equal left and right gauge couplings) we find the S parameter to be ∼ 1.15, while T ∼ U ∼ 0,(More)
We study the motion of an n-brane in an n + q + 2 dimensional background that has dilatonic q-brane singularities and that is charged under an antisymmetric tensor field. The background spacetime is maximally symmetric in the n-dimensions parallel to the n-brane with constant curvature k = 0,±1. For k = 1 the bulk solutions correspond to black q-branes. For(More)
We consider extra dimensional descriptions of models where there are two separate strongly interacting sectors contributing to electroweak symmetry breaking (“topcolor” type models). In the extra dimensional picture there would be two separate (anti-de Sitter) bulks meeting on the Planck brane, with each bulk having its own corresponding IR (TeV) brane.(More)
The hierarchy problem and the electroweak data, together, provide a plausible motivation for considering a light Higgs emerging as a pseudo-Goldstone boson from a strongly-coupled sector. In that scenario, the rates for Higgs production and decay differ significantly from those in the Standard Model. However, one genuine strong coupling signature is the(More)
We study deformations of the SM via higher dimensional operators. In particular, we explicitly calculate the one-loop anomalous dimension matrix for 13 bosonic dimension-6 operators relevant for electroweak and Higgs physics. These scaling equations allow us to derive RG-induced bounds, stronger than the direct constraints, on a universal shift of the Higgs(More)
Electroweak interactions need three Nambu–Goldstone bosons to provide a mass to the W ± and the Z gauge bosons but they also need an ultraviolet (UV) moderator or new physics to unitarize the gauge boson scattering amplitudes. In this talk, I will present various recent models of physics at the Fermi scale: several deformations of the Minimal Supersymmetric(More)