Transverse parton distribution functions at next-to-next-to-leading order: the quark-to-quark case

Thomas Gehrmann, Thomas Lübbert, Li Lin Yang

Published 2012-09-04, updated 2012-11-05Version 2

We present a calculation of the perturbative quark-to-quark transverse parton distribution function at next-to-next-to-leading order based on a gauge invariant operator definition. We demonstrate for the first time that such a definition works beyond the first non-trivial order. We extract from our calculation the coefficient functions relevant for a next-to-next-to-next-to-leading logarithmic $Q_T$ resummation in a large class of processes at hadron colliders.