Three-gluon decays of radially excited quarkonia $\psi (2S)$ and ${\rm Y}(2S)$ with both relativistic and QCD radiative corrections

Chao-Jie Fan, Jun-Kang He

For the radially excited heavy quarkonia $V=\psi (2S)$ and ${\rm Y}(2S)$, the nodal structure of the wave function renders the three-gluon decay $V\to ggg$ acutely sensitive to relativistic…