2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/43366We study the effects of heavy Higgs bosons on the top-pair production process at photon linear colliders. The interference patterns between the resonant Higgs-production amplitudes and the continuum QED amplitudes are examined. The patterns tell us not only the CP nature of the Higgs bosons but also the phase of the $γγ$--Higgs vertex which gives new information about the Higgs couplings to new charged particles.To appear in the Proceedings of SUSY 2003, held at the University of Arizona, Tucson, AZ, 5-10 June 2003High Energy Physics - Phenomenologytext