Probing light pseudoscalar, axial vector states through ${\eta }_b\to {\tau }^{+}{\tau }^{-}$

Abstract

In this paper we explore the decay ${\eta }_b-->{\tau }^{+}{\tau }^{-}$ as a probe for a light pseudoscalar or a light axial vector state. We estimate the standard model branching ratio for this decay to be $4\times 10^{-9}$. We show that considerably larger branching ratios, up to the present experimental limit of ~8%, is possible in models with a light pseudoscalar or a light axial vector state. As we do not include possible mixing effects between the light pseudoscalar and the ${\eta }_b$, our results should be reliable when the pseudoscalar mass is away from the ${\eta }_b$ mass.

Comments: 14 pages, 6 figures. Version accepted for publication in PRD