Observation of $ψ(3686) \to p \bar{p} η^{\prime}$ and improved measurement of $J/ψ\to p \bar{p} η^{\prime}$

Abstract

We observe the process ψ(3686) → ppη ′ for the first time, with a statistical significance higher than 10σ, and measure the branching fraction of J/ψ → ppη ′ with an improved accuracy compared to earlier studies. The measurements are based on 4.48 × 10 8 ψ(3686) and 1.31 × 10 9 J/ψ events collected by the BESIII detector operating at the BEPCII. The branching fractions are determined to be B(ψ(3686) → ppη ′ ) = (1.10 ± 0.10 ± 0.08) × 10 −5 and B(J/ψ → ppη ′ ) = (1.26 ± 0.02 ± 0.07) × 10 −4 , where the first uncertainties are statistical and the second ones systematic. Additionally, the η − η ′ mixing angle is determined to be −24 • ± 11 • based on ψ(3686) → ppη ′ , and −24 • ± 9 • based on J/ψ → ppη ′ , respectively.

Selecting the physical solution via $η$-$η'$ mixing

“…Then it would be instructive to readdress Eqs. 1 in terms of quark components for η 8 and η 0 as [11,12]…”