Abstract: Factorization theorems are known to be extremely powerful tools in high-energy particle physics. Processes like SIDIS, Drell-Yan vector-boson production, Higgs-boson production through gluon fusion and electron-positron annihilation to jets and/or hadrons are just some examples of processes that have been thoroughly investigated by applying rigorous factorization formulae. Furthermore, if in these processes the transverse momentum qT of the vector boson or final-state hadrons is measured, then in the limit of small qT, leading-power transverse-momentum-dependent (TMD) factorization is an established tool to obtain further insight into the internal structure of the hadrons involved (like spin and helicity distributions, sea quark contributions).

However, in order to properly exploit increasingly precise experimental data, it is important to investigate sub-leading contributions. In this talk, we present a novel method to compute next-to-leading-power and next-to-next-leading-power contributions to TMD cross sections. In the specific case of a Drell-Yan process, we show how our analytic results allow us to achieve next-to-next-to-leading logarithmic (NNLL) resummation, recover both the leading-power TMD factorization and collinear factorization expressions up to next-to-next-to-leading order in the small-qT limit and providea description of the cross section valid also at intermediate qT. The implications for the phenomenological extraction of TMDPDFs are also discussed.