LEP1 vs. Future Colliders: Effective Operators And Extended Gauge Group
  In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an extended gauge group context. 
J.-M. Fr\`ere J.M. Moreno M. Tytgat J. Orloff