摘要
Photon-photon linear colliders can be realized by the laser back-scattering technique in the next-generation linear e+e- colliders. Here the associated productions of an intermediate-mass Higgs (IMH) or Z boson with a tt̄ pair in γγ collisions are studied. Since IMH is very unlikely to decay into a tt̄ pair, tt̄H production is the only direct channel to probe the Higgs-top Yukawa coupling in the case of an IMH. tt̄Z production can be a potential background to tt̄H if the Higgs mass is close to mZ. As an alternative to its parent e+e- collider, γγ→tt̄H(Z) productions are compared with the corresponding productions in the e+e- collisions. © 1993 The American Physical Society.