The BESIII experiment has accumulated the world’s largest data samples of 1.3 billion J/ψ events and 0.45 billion ψ(3686) events, which provide a unique opportunity to investigate light meson decays. The η and η′ decays are sensitive tools for investigations of π − π and η − π interactions, symmetry breaking, and serve as a test of chiral perturbation theory. In recent years considerable results on η and η′ decays were achieved at the BESIII experiment. In this proceeding, we present the significant progresses on amplitude analyses of Dalitz decays η' → 3π,η' → ηππ, and radiative decay η' → γπ+π−, η' → γγπ0. Additionally, the $a_0^0\left( {980} \right) - {f_0}\left( {980} \right)$ mixing is an important probe to the nature of those two lightest scalar mesons. The first observation of $a_0^0\left( {980} \right) - {f_0}\left( {980} \right)$ mixing is also presented, which will help to improve the understanding of the nature of $a_0^0\left( {980} \right)$ and f0(980).
Signals of the QCD axion with mass of
17 MeV/c2
: Nuclear transitions and light meson decays