Zeros of the WLZL → WLZL amplitude: where vector resonances stand

A Higgsless electroweak theory may be populated by spin-1 resonances around E similar to 1 TeV as a consequence of a new strong interacting sector, frequently proposed as a tool to smear the high-energy behaviour of scattering amplitudes, for instance, 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 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 to identify the parameter space region of the low-energy couplings where vector resonances may arise. An estimate of their masses is also provided by our method.