Potential of Photon Collider in resolving SM-like scenarios

After operations at the LHC and e(+)e(-) Linear Colliders, it may be found that a Standard-Model-like (SM-like) scenario is realized. In this scenario, no new particle will be discovered, except a single Higgs boson having partial widths or coupling constants squared with fundamental particles close, within anticipated experimental uncertainty, to those of the SM. Experiments at a Photon Collider can resolve whether the SM model or e.g. the Two-Higgs-Doublet Model is realized in Nature. For the SM-like version of the 2HDM (II), we study the loop couplings of the Higgs boson with gamma gamma and Z gamma, and also with gluons. The deviation of the two-photon width from its SM value is generally higher than the expected inaccuracy in the measurement of Gamma (gamma gamma) at a Photon Collider. The result is sensitive to the parameters of the Higgs self interaction. (C) 2001 Elsevier Science B.V, All rights reserved.