Transverse Parton Distribution and Fragmentation Functions at NNLO: the Quark Case

Understand

We revisit the calculation of perturbative quark transverse momentum dependent parton distribution functions and fragmentation functions using the exponential regulator for rapidity divergences.

• We show that the exponential regulator provides a consistent framework for the calculation of various ingredients in transverse momentum dependent factorization.
• Compared to existing regulators in the literature, the exponential regulator has a couple of advantages which we explain in detail.
• As a result, the calculation is greatly simplified and we are able to obtain the next-to-next-to-leading order results up to $\mathcal{O}(\epsilon^2)$ in dimensional regularization.