Higgs Searches at Future Colliders : Potentials for Discovery and Diagnosis ∗

The prospects for Higgs boson discovery and study at present and future colliders are reviewed, with emphasis on the Minimal Supersymmetric Standard Model (MSSM) states. The expected experimental coverages with different production and decay modes are outlined. Particular attention is given to the Higgs couplings predicted when the top quark Yukawa coupling has an infrared fixed point. Characteristic Higgs boson mass spectra from the minimal supergravity (mSUGRA) model are considered and the decoupling/non-decoupling regimes of the lightest Higgs boson are discussed. General tests are described to ascertain whether a discovered light Higgs boson is a SM or MSSM state and to diagnose its fundamental properties. The constraints on the Higgs mass spectra implied by an interesting cosmological relic density of the lightest supersymmetric particle are described.