O(αsµ2) corrections to hadronic and electromagnetic decays of 1S0 heavy quarkonium.

We study O(αsv2) corrections to decays of 1S0 heavy quarkonium into light hadrons and two photons within the framework of nonrelativistic QCD and find these O(αsv2) corrections to have significant contributions especially for the decay into light hadrons. With these new results, experimental measurements of the hadronic width and the γγ width of ηc can be described more consistently. By fitting experimental data, we find the long-distance matrix elements of ηc to be ∣Rηc(0)∣2=0.834-0.197+0.281??GeV3 and «v2»ηc=0.232-0.098+0.121. Moreover, ηc(2S) is also discussed and the γγ decay width is predicted to be 3.34-2.10+2.06??KeV. [ABSTRACT FROM AUTHOR]