Résumé
In the spirit of the Composite Standard Model (CSM) we look at the effect of $H$, $Z_L$ compositeness on $ZH$ production in gluon-gluon and photon-photon collisions. Because they would perturb the basic cancellations occuring in SM amplitudes, such compositeness effects would lead to spectacular modifications of the energy dependence of the amplitudes and cross sections. We illustrate this fact by introducing $H$, $Z_L$ test form factors and computing the corresponding differential cross section and the fraction of longitudinal $Z_L$ production.