Towards the (Mexican) discovery of second class currents at Belle-II

Abstract

Within the SM, the yet unmeasured ${\tau }^{-}\to {\pi }^{-}{\eta }^{(\prime )}{\nu }_{\tau }$ decays are predicted as a suppressed, isospin-violating effect with branching ratios $\lesssim \mathcal{O}(10^{-5})$. However, they can also proceed through other mechanisms (such as charged Higgs exchange) at comparable rates. This has motivated several studies of the corresponding QCD predictions for these second class current processes. In this contribution we discuss the prospects for the discovery of these decays at Belle-II emphasizing the Mexican involvement in this project. Our branching ratio prediction $\sim 1.7\cdot 10^{-5}$ (decay channel with an $\eta$ meson) is well within the reach of Belle-II. The branching fraction for the decay channel with an ${\eta }^{\prime }$ meson is expected to be between one and two orders of magnitude more suppressed.

9 pages, 5 figures. To be published in Journal of Physics Conference Series (IOP). Joint Proceedings of the XV Mexican Workshop on Particles and Fields & the XXX Annual Meeting of the Division of Particles and Fields of the Mexican Physical Society

References in corpus (6)

• Measurement of the pseudoscalar mixing angle and ${\eta }^{\prime }$ gluonium content with KLOE detector
• Combined analysis of the decays ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{-}\to K^{-}\eta {\nu }_{\tau }$
• Estimate of the branching fraction ${\tau }^{-}\to \eta {\pi }^{-}{\nu }_{\tau }$, the $a_0^{-}(980)$, and non-standard weak interactions
• Estimate of the Branching Fraction of tau --> pi eta' nu_tau
• On the branching ratio of the "second class" tau --> eta' pi nu_tau decay
• Search for $\eta$ and ${\eta }^{\prime }\to {\pi }^{+}{e}^{-}{\bar{\nu }}_e+c.c.$ decays in $\jpsi \to ϕη$ and $\varphi {\eta }^{\prime }$

Cited by in corpus (1)

• ${\tau }^{-}\to {\eta }^{(\prime )}{\pi }^{-}{\nu }_{\tau }\gamma$ decays as backgrounds in the search for second class currents