Zeros of the $W_L Z_L \rightarrow W_L Z_L$ amplitude: With or without a light Higgs

TL;DR

This paper investigates how the zeros of the scattering amplitude for W_L Z_L interactions can reveal the presence of heavy vector resonances in electroweak theories, with or without a light Higgs, using effective field theory methods.

Contribution

It introduces a method to identify parameter regions where vector resonances may appear by analyzing the zeros of the electroweak scattering amplitude within the chiral effective theory.

Findings

Zeros of the amplitude indicate potential vector resonances.

The approach applies to theories with or without a light Higgs.

Parameter space regions for resonances are characterized.

Abstract

The existence of a new strong interacting sector around E ~ 1 TeV is a common feature of Higgsless electroweak theories but also of theories with a light Higgs, for instance, when this is not elementary. In those schemes, this new interaction could be at the origin of an extended spectra with, in particular, spin-1 resonances that could be hinted in elastic gauge boson scattering. Information on those resonances, if they exist, must be contained in the low-energy couplings of the electroweak chiral effective theory. Using the facts that: i) the scattering of longitudinal gauge bosons, W_L, Z_L, can be well described in the high-energy region (E >> M_W) by the scattering of the corresponding Goldstone bosons (equivalence theorem) and that ii) the zeros of the scattering amplitude carry the information on the heavier spectrum that has been integrated out; we employ the O(p^4) electroweak chiral Lagrangian, with or without a light Higgs state to identify the parameter space region of the low-energy couplings where vector resonances may arise.