Quasi-Transverse Momentum Dependent PDFs from Lattice QCD

Transverse momentum distributions are a key observable at high-energy colliders such as the LHC and an important probe of the proton structure. They are obtained in terms of transverse-momentum dependent PDFs (TMDPDFs), which at small transverse momenta become genuinely nonperturbative objects. I will discuss the possibility to calculate them directly using lattice QCD, based on the method of quasi PDFs which has already been successfully applied to PDFs. After giving a brief review of quasi PDFs, I will introduce the framework of TMDPDFs and show to what extent they can be obtained from lattice. In particular, it is shown that lattice QCD provides direct access to the nonperturbative evolution of TMDPDFs encoded in the Collins-Soper kernel.