Is the b quark mixed with a vectorlike quark?

Abstract

We examine the possibility of an exotic vectorlike charge (-1/3) quark h mixing with the d-type quarks. The currently accepted Cabibbo-Kobayashi-Maskawa matrix elements, though consistent with unitarity, allow substantial mixing of such an exotic quark with the b quark. Concentrating on h-b mixing, we find several distinctive signatures-in top-quark production and decay, Z→ bb̅ , and flavor-violating rare Z decays-which may be experimentally testable in the near future.