Determination of the Collins-Soper kernel from cross-sections ratios

The Collins-Soper kernel is a powerful tool for studying the properties of the QCD vacuum and an essential component of the transverse momentum dependent (TMD) factorization theorem. In this paper, we present a novel method for determining the Collins-Soper kernel directly from the comparison of differential cross sections measured at different energies. The method relies solely on the structure of the TMD factorization theorem and thus also provides a direct test of the theorem validity. With minor modifications, the procedure can be applied to the real measured data for Drell-Yan and SIDIS processes. As a demonstration, we analyze the pseudodata generated by the CASCADE event generator and determine the Collins-Soper kernel suggested by the parton branching model.