Linear collider physics

The International Linear Collider has a rich physics programme, whatever lies beyond the standard model. Accurate measurement of the top quark mass is needed to constrain the model or its extensions. If there is a light Higgs boson the LHC should see it, but the ILC will pin down its characteristics and test them against model predictions. If Supersymmetric particles appear the ILC will measure a complementary set of them to those seen at the LHC, and may allow extrapolation to the Grand Unified scale. And if a strong electroweak sector is indicated the ILC will be sensitive to the presence of new structures in difermion and diboson systems up to higher masses than the direct search range of the LHC. Beyond the LHC and ILC there could be need for a multi TeV lepton collider.