Fourth-generation and exotic quarkonium in E6 theories.

Abstract

Hypothetical fourth-generation quarks of charge -(1/3) and exotic quarks from ${\mathrm{E}}_{6}$ theories can each form quarkonia bound states. Since both systems have identical strong and electromagnetic properties, the only hope of distinguishing these two quarkonia is to examine their weak interactions. In this paper we analyze several decay modes of these systems (such as, QQ\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}qq\ifmmode\bar\else\textasciimacron\fi{}, ${l}^{+}$${l}^{\mathrm{\ensuremath{-}}}$ \ensuremath{\nu}\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{},. . .) and find quite different decay rates for the cases of fourth-generation and ${\mathrm{E}}_{6}$ exotic quarkonia over a wide range of masses. Thus the weak interactions do provide a means for distinguishing between these two possible systems.