Miguel G. Echevarria, Ahmad Idilbi, Andreas Schäfer, Ignazio Scimemi
We present a new approach to treat the perturbative QCD evolution of TMDs by resummation. We obtain a universal evolution kernel for the eight quark distributions while large logarithms are resummed up to next-to-next-to leading logarithms (NNLL). Contrary to earlier works this resummation gives unambiguous predictions avoiding the need to introduce an ad-hoc cut-off parameters and thus highly reducing the model-dependence. Applications to single-spin asymmetries, as the Sivers function, and unpolarized transverse-momentum-dependent parton distribution functions are given. The results agree very well with phenomenology.
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http://arxiv.org/abs/1208.1281
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