We present a calculation of next-to-leading-order (NLO) QCD corrections to total hadronic production cross sections and to light-hadron-decay rates of heavy quarkonium states. Both colour-singlet and colour-octet contributions are included. We discuss in detail the use of covariant projectors in dimensional regularization, the structure of soft-gluon emission and the overall finiteness of radiative corrections. We compare our approach with the NLO version of the threshold-expansion technique recently introduced by Braaten and Chen. Most of the results presented here are new. Others represent the first independent reevaluation of calculations already known in the literature. In this case a comparison with previous findings is reported.

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We present in this work a study of large-p T charmonium production in hadronic collisions. We work in the framework of the factorization model of Bodwin Braaten and Lepage, thereby including the color octet production mechanism, and extract the values of the necessary nonperturbative parameters from a comparison with the most recent data from the Fermilab 1.8 TeV pp hadron collider. We extend the calculation to 630 GeV, and compare the results with data published by the UA1 Collaboration. The global agreement is satisfactory, indicating that the largest components of the production mechanisms for charmonium production at high p T have been isolated.

We investigate the effects of color-octet contributions to the radiative ⌼ decay within the Bodwin, Braaten, and Lepage nonrelativistic QCD ͑NRQCD͒ framework. We compute the short-distance coefficients at next-toleading order ͑NLO͒ in ␣ s for the most relevant color-octet intermediate states and consider photons coming both from the coupling to hard processes ͑''direct''͒ and by collinear emission from light quarks ͑''fragmentation''͒. An estimate for the nonperturbative matrix elements which enter in the final result is then obtained. By comparing the NRQCD prediction at NLO for total decay rates with the experimental data, it is found that the nonperturbative parameters must be smaller than expected from the naive scaling rules of NRQCD. Nevertheless, color-octet contributions to the shape of the photon spectrum turn out to be significant.