Novel approach to investigate $η$ decays via $η'\rightarrowππη$

Abstract

To avoid the impact from the background events directly from $e^+e^-$ annihilations or $J/ψ$ decays, we propose a novel approach to investigate $η$ decays, in particular for its rare or forbidden decays, by using $η^\prime\rightarrowππη$ produced in $J/ψ$ decays at the $τ-$charm factories. Based on the MC studies of a few typical decays, $η\rightarrow ππ$, $γl^+l^- (l= e, μ)$, $l^+l^-$, as well as $l^+l^-π^0$, the sensitivities could be obviously improved by taking advantage of the extra constraint of $η^\prime$. Using one trillion $J/ψ$ events accumulated at the Super $τ$-Charm facility, the precision on the investigation of $η$ decays could be improved significantly and the observation of the rare decay $η\rightarrow e^+e^-$ is even accessable.

7 pages, 6 figures