Speaker
Mr
Matthew Reece
(Cornell University, Laboratory for Elementary Particle Physics)
Description
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 5D theory. Therefore, our work
strongly suggests that S is positive in calculable models in extra dimensions.
Authors
Christophe Grojean
(CERN theory division and Service de Physique Theorique, CEA Saclay)
Csaba Csaki
(Cornell University)
Kaustubh Agashe
(Syracuse University)
Mr
Matthew Reece
(Cornell University, Laboratory for Elementary Particle Physics)