Two-parton twist-3 factorization in perturbative QCD
نویسندگان
چکیده
Abstract We prove collinear factorization theorem for the process πγ∗ → π at the twist-3 level in the covariant gauge by means of the Ward identity, concentrating on the two-parton case. It is shown that soft divergences cancel and collinear divergences are grouped into the pseudo-scalar and pseudotensor two-parton twist-3 pion distribution amplitudes. The delicate summation of a complete set of diagrams for achieving factorization in momentum, spin, and color spaces is emphasized. The proof is then extended to the exclusive semileptonic decay B → πlν̄, assuming the hard scale to be of O( √
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تاریخ انتشار 2005