1
From a Breit-Wigner fit involving 9 resonances and a resonating exotic ${{\mathit \eta}_{{{1}}}{(1855)}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \eta}^{\,'}}{\mathit P}{\mathrm -wave}$.
2
From a partial wave analysis of the systems (${{\mathit \gamma}}{{\mathit X}}$), with ${{\mathit X}}$ $\rightarrow$ ${{\mathit \eta}^{\,'}}{{\mathit \eta}^{\,'}}$, and (${{\mathit \eta}^{\,'}}{{\mathit X}}$), with ${{\mathit X}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}^{\,'}}$ in the decay ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \eta}^{\,'}}{{\mathit \eta}^{\,'}}$. The intermediate resonance ${{\mathit X}}$ is parametrized by a constant-width, relativistic Breit-Wigner.
3
T-matrix pole from coupled channel K-matrix fit to data on ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$ (ABLIKIM 2015AE) and ${{\mathit J / \psi}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit K}_S^0}$ ${{\mathit K}_S^0}$ (ABLIKIM 2018AA).
4
Partial wave analysis of the data on ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\overline{\mathit \Lambda}}}{{\mathit \Lambda}}$ from BARNES 2000.
References:
ABLIKIM
2022AS
PR D106 072012
Partial wave analysis of
Also
PR D107 079901 (errat.)
Partial wave analysis of
ABLIKIM
2022C
PR D105 072002
Partial wave analysis of $J/\psi \rightarrow \gamma \eta' \eta'$
RODAS
2022
EPJ C82 80
Scalar and tensor resonances in $J/\psi $ radiative decays
SARANTSEV
2021
PL B816 136227
Scalar isoscalar mesons and the scalar glueball from radiative $J/\psi$ decays
