O(αsv2)corrections to hadronic and electromagnetic decays ofS01heavy quarkonium

Abstract

We study $O({\ensuremath{\alpha}}_{s}{v}^{2})$ corrections to decays of $^{1}S_{0}$ heavy quarkonium into light hadrons and two photons within the framework of nonrelativistic QCD and find these $O({\ensuremath{\alpha}}_{s}{v}^{2})$ corrections to have significant contributions especially for the decay into light hadrons. With these new results, experimental measurements of the hadronic width and the $\ensuremath{\gamma}\ensuremath{\gamma}$ width of ${\ensuremath{\eta}}_{c}$ can be described more consistently. By fitting experimental data, we find the long-distance matrix elements of ${\ensuremath{\eta}}_{c}$ to be $|{\mathcal{R}}_{{\ensuremath{\eta}}_{c}}(0){|}^{2}={0.834}_{\ensuremath{-}0.197}^{+0.281}\text{ }\text{ }{\mathrm{GeV}}^{3}$ and $⟨{\mathbit{v}}^{2}{⟩}_{{\ensuremath{\eta}}_{c}}={0.232}_{\ensuremath{-}0.098}^{+0.121}$. Moreover, ${\ensuremath{\eta}}_{c}(2S)$ is also discussed and the $\ensuremath{\gamma}\ensuremath{\gamma}$ decay width is predicted to be ${3.34}_{\ensuremath{-}2.10}^{+2.06}\text{ }\text{ }\mathrm{KeV}$.