1
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.
2
From a Breit-Wigner fit involving 9 resonances and a resonating exotic ${{\mathit \eta}_{{{1}}}{(1855)}}$ $\rightarrow$ ${{\mathit \eta}}{{\mathit \eta}^{\,'}}{\mathit P}{\mathrm -wave}$.
Partial wave analysis of $J/\psi \rightarrow \gamma \eta' \eta'$
ABLIKIM
2022AS
PR D106 072012
Partial wave analysis of
Also
PR D107 079901 (errat.)
Partial wave analysis of
UMAN
2006
PR D73 052009
Light Quark Resonances in ${{\overline{\mathit p}}}{{\mathit p}}$ Annihilations at 5.2 GeV/$\mathit c$
ANISOVICH
2000J
PL B491 47
I = 0 C = +1 Mesons from 1920 to 2410 MeV
ALDE
1998
EPJ A3 361
Study of the ${{\mathit \pi}^{0}}$ ${{\mathit \pi}^{0}}$ System with the GAMS-4000 Spectrometer at 100 ${\mathrm {GeV/}}\mathit c$
Also
PAN 62 405
Investigation of the ${{\mathit \pi}^{0}}$ ${{\mathit \pi}^{0}}$ System at a Primary Momentum of 100 ${\mathrm {GeV/}}\mathit c$ by using the GAMS-4000 Spectrometer
