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Twist-3 contributions to processes in perturbative QCD approach
As one of the simplest hadronic processes, () could be a good testing ground for our understanding of
the perturbative and nonperturbative structure of QCD, and will be studied with
high precision at BELLE-\RNum{2} in the near future. In this paper, we revisit
these processes with twist-3 corrections in the perturbative QCD approach based
on the factorization theorem, in which transverse degrees of freedom as
well as resummation effects are taken into account. The influence of the
distribution amplitudes on the cross sections are discussed in detail. Our work
shows that not only the transverse momentum effects but also the twist-3
corrections play a significant role in the processes in the intermediate energy region. Especially in the few GeV
region, the twist-3 contributions become dominant in the cross sections. And it
is noteworthy that both the twist-3 result of the cross
section and that of the cross section agree well with the BELLE
and ALEPH measurements. For the pion and kaon angular distributions, there
still exist discrepancies between our results and the experimental
measurements. Possible reasons for these discrepancies are discussed briefly.Comment: 19 pages, 7 figures and 2 tables. Contents improved and more
discussions adde
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