Determination of the Collins-Soper Kernel from Lattice QCD

We present lattice results for the non-perturbative Collins-Soper (CS) kernel, which describes the energy-dependence of transverse momentum-dependent parton distributions (TMDs). The CS kernel is extracted from the ratios of first Mellin moments of quasi-TMDs evaluated at different nucleon momenta. The analysis is done with dynamical N_f = 2 + 1 clover fermions for the CLS ensemble H101 (a = 0.0854 fm, m_π = m_K = 422 MeV). The computed CS kernel is in good agreement with experimental extractions and previous lattice studies.