Abstract :
We analyze the perturbative and parametric stability of the QCD predictions for the azimuthal asymmetries in heavy quark leptoproduction. At leading order, the cosϕ asymmetry vanishes whereas the cos2ϕ one is of leading twist and predicted to be about 15% at energies sufficiently above the production threshold. We calculate the NLO soft-gluon corrections to ϕ-dependent leptoproduction to the next-to-leading logarithmic accuracy. The soft-gluon approximation provides a good description of the available exact NLO results at Q2≲m2. Our analysis shows that, contrary to the production cross sections, the cos2ϕ asymmetry is practically insensitive to soft radiation for Q2≲m2 at energies of the fixed target experiments. We conclude that the cos2ϕ asymmetry is well defined in pQCD: it is stable both perturbatively and parametrically, and insensitive (in the case of bottom production) to nonperturbative contributions. Measurements of the azimuthal asymmetries would provide an excellent test of pQCD applicability to heavy flavor production.
