Zeros of the $W_L{Z}_L\to W_L{Z}_L$ amplitude: With or without a light Higgs

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.

Comments: Talk at the 7th International Workshop on Chiral Dynamics, August 6-10, 2012, Thomas Jefferson National Accelerator Facility, 7 pages, 2 figures