title: Viability of strongly coupled scenarios with a light Higgs-like boson.
abstract: We present a one-loop calculation of the oblique S and T parameters within strongly coupled models of electroweak symmetry breaking with a light Higgs-like boson. We use a general effective Lagrangian, implementing the chiral symmetry breaking SU(2)(L) [Symbol: see text]SU(2)(R) → SU(2)(L+R) with Goldstone bosons, gauge bosons, the Higgs-like scalar, and one multiplet of vector and axial-vector massive resonance states. Using a dispersive representation and imposing a proper ultraviolet behavior, we obtain S and T at the next-to-leading order in terms of a few resonance parameters. The experimentally allowed range forces the vector and axial-vector states to be heavy, with masses above the TeV scale, and suggests that the Higgs-like scalar should have a WW coupling close to the standard model one. Our conclusions are generic and apply to more specific scenarios such as the minimal SO(5)/SO(4) composite Higgs model.
authors.affiliation: Departament de Física Teòrica, IFIC, Universitat de València-CSIC, Apartat de Correus 22085, 46071 València, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pich
authors.forename: Ignasi
authors.initials: I
authors.lastname: Rosell
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Sanz-Cillero