%0 Journal Article %T Associated production of Intermediate Higgs or Z-boson with $t \bar t$ pair in $¦Ã¦Ã$ collision %A Kingman Cheung %J Physics %D 1992 %I arXiv %R 10.1103/PhysRevD.47.3750 %X Photon-photon linear colliders can be realized by laser back-scattering technique on the next generation linear $e^+e^-$ colliders. Here the associated productions of an intermediate mass Higgs (IMH) or Z-boson with $t \bar t$ pair in $\gamma\gamma$ collisions are studied. Since IMH is very unlikely to decay into $t\bar t$ pair, $t\bar tH$ production is the only direct channel to probe the Higgs-top Yukawa coupling in case of an IMH. $t\bar tZ$ production can be a potential background to $t\bar tH$ if the Higgs mass is close to $m_Z$. As an alternative to its parent $e^+e^-$ collider, $\gamma\gamma \to t\bar tH(Z)$ productions are compared with the corresponding productions in the $e^+e^-$ collisions. %U http://arxiv.org/abs/hep-ph/9211262v1