W-BOSON LOOP BACKGROUND TO H-]ZZ AT PHOTON-PHOTON COLLIDERS

We have performed a complete one-loop calculation of gamma gamma-->ZZ in the standard model, including both gauge bosons and fermions in the loop. We confirm the large irreducible continuum background from the W boson loop found by Jikia. We have included the photon-photon luminosity, and find that the continuum background of transverse Z boson pairs prohibits finding a heavy Higgs boson with a mass greater than or similar to 350 GeV in this decay mode.