Limits on Pseudoscalar Bosons From Rare $Z$ Decays at LEP

Abstract

Current LEP data on rare $Z$ decays constrain nonminimal technicolor models that contain light neutral pseudo-Nambu-Goldstone bosons ($P^a$). We discuss the production and decay of such particles, and show how LEP data on $\gamma\gamma\gamma$, $\gamma + E\!\!\!/ $ and $\gamma+$hadrons constrain the size of the technicolor gauge group and the strength of the $Z\gamma P^a$ coupling. The limits are then applied to several specific technicolor scenarios.