6533b86efe1ef96bd12cbeaa
RESEARCH PRODUCT
One-loop calculation of the oblique S parameter in higgsless electroweak models
Juan José Sanz-cilleroIgnasi RosellIgnasi RosellAntonio Pichsubject
PhysicsNuclear and High Energy PhysicsGauge bosonParticle physicsElectroweak interactionHigh Energy Physics::PhenomenologyFOS: Physical sciencesFísicaHigh Energy Physics - PhenomenologyHigh Energy Physics - Phenomenology (hep-ph)High Energy Physics::ExperimentSymmetry breakingSum rule in quantum mechanicsGauge theoryOperator product expansionChiral symmetry breakingMultipletdescription
We present a one-loop calculation of the oblique S parameter within Higgsless models of electroweak symmetry breaking and analyze the phenomenological implications of the available electroweak precision data. We use the most general effective Lagrangian with at most two derivatives, implementing the chiral symmetry breaking SU(2)_L x SU(2)_R -> SU(2)_{L+R} with Goldstones, gauge bosons and one multiplet of vector and axial-vector massive resonance states. Using the dispersive representation of Peskin and Takeuchi and imposing the short-distance constraints dictated by the operator product expansion, we obtain S at the NLO in terms of a few resonance parameters. In asymptotically-free gauge theories, the final result only depends on the vector-resonance mass and requires M_V > 1.8 TeV (3.8 TeV) to satisfy the experimental limits at the 3 \sigma (1\sigma) level; the axial state is always heavier, we obtain M_A > 2.5 TeV (6.6 TeV) at 3\sigma (1\sigma). In strongly-coupled models, such as walking or conformal technicolour, where the second Weinberg sum rule does not apply, the vector and axial couplings are not determined by the short-distance constraints; but one can still derive a lower bound on S, provided the hierarchy M_V 1.8 TeV.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2012-06-15 |