Indirect Searches for Very Heavy Quarksa

Abstract

Detailed studies of weak decays can reveal the presence of very massive quanta like heavy top quarks or fourth family quarks. The decay K+ --) ?~+vP and Bd - Ba mixing are particularly promising fields for such searches. We infer a rather conservative lower limit of 70 GeV on the top mass from recent ARGUS data on Bd - Bd mixing; near-maximal B, - Bd mixing is another consequence. If on the other hand top were detected in Z” decays, then the presence of New Physics would be established in B” decays. The ratio between r(B”) and r(B*) is of considerable phenomenological relevance here.