Implications of unitarity for low-energyWL±,ZLscattering

We investigate the partial-wave scattering of longitudinally polarized $W^{\pm }$ and $Z$ bosons for energies $M_W\ll \sqrt{s}\ll M_H$ using an Argand-diagram analysis. We find that, for large Higgs-boson masses $M_H$, partial-wave unitarity is badly violated at one loop at energies $\sqrt{s}\ll M_H$, and the standard model of the electroweak interactions becomes effectively strongly interacting in this sector. The implications of this and other similar results are summarized.