Vector Resonances from a Strong Electroweak Sector at Linear Colliders

We explore the usefulness of very energetic linear $e^+e^-$ colliders in the $TeV$ range in studying an alternative scheme of electroweak symmetry breaking based on a strong interacting sector. The calculations are performed within the BESS model which contains new vector resonances. If the mass $M_V$ of the new boson multiplet lies not far from the maximum machine energy, or if it is lower, such a resonant contribution would be quite manifest. A result of our analysis is that also virtual effects are important. It appears that annihilation into a fermion pair in such machines, at the considered luminosities, would improve only marginally on existing limits if polarized beams are available and left-right asymmetries are measured. On the other hand, the process of $W$-pair production by $e^+e^-$ annihilation would allow for sensitive tests of the hypothesized strong sector, especially if the $W$ polarizations are reconstructed from their decay distributions, and the more so the higher the energy of the machine. An $e^+e^-$ collider with c.m. energy $\sqrt{s}=500~GeV$ could improve the limits on the model for the range $500<M_V(GeV)<1000$ when $W$ polarization is not reconstructed. If $W$ polarizations are reconstructed, then the bounds improve for the entire expected range of $M_V$. These bounds become more stringent for larger energy of the collider. We have also studied the detectability of the new resonances through the fusion subprocesses, but this channel does not seem to be interesting even for a collider with a c.m. energy $\sqrt{s}=2~TeV$.