Heavy Resonances in the Electroweak Effective Lagrangian

TL;DR

This paper develops a simplified electroweak effective Lagrangian incorporating heavy vector and axial-vector states, analyzing their low-energy effects and phenomenological constraints, suggesting possible strongly-coupled scenarios above the TeV scale.

Contribution

It introduces a new simplified framework for including heavy vector states in the electroweak effective theory with phenomenological analysis.

Findings

Heavy vector states can exist above the TeV scale consistent with current data.

The framework incorporates short-distance constraints and electroweak symmetry breaking.

Phenomenological constraints from S and T parameters are analyzed at next-to-leading order.

Abstract

As a first step towards the construction of a general electroweak effective Lagrangian incorporating heavy states, we present here a simplified version where only vector and axial-vector spin-1 triplets are involved. We adopt an effective field theory formalism, implementing the electroweak chiral symmetry breaking SU(2)L x SU(2)R -> SU(2)L+R, which couples the heavy states to the SM fields. At low energies, the heavy degrees of freedom are integrated out from the action and their effects are hidden in the low-energy couplings of the Electroweak Effective Theory, which can be tested experimentally. Short-distance constraints are also implemented, requiring a proper behaviour in the high-energy regime. We analyze the phenomenological constraints from the oblique parameters S and T , at the next- to-leading order. Our results show that present data allow for strongly-coupled scenarios with massive bosons above the TeV scale.