  We present the first lattice QCD calculation of the rapidity anomalous
dimension of transverse-momentum-dependent distributions (TMDs), i.e. the
Collins-Soper (CS) kernel, employing the recently proposed Coulomb-gauge-fixed
quasi-TMD formalism as well as a chiral-symmetry preserving lattice
discretization. This unitary lattice calculation is conducted using the domain
wall fermion discretization scheme, a fine lattice spacing of approximately
0.08 fm, and physical values for light and strange quark masses. The CS kernel
is determined analyzing the ratios of pion quasi-TMD wave functions
(quasi-TMDWFs) at next-to-leading logarithmic (NLL) perturbative accuracy.
Thanks to the absence of Wilson-lines, the Coulomb-gauge-fixed quasi-TMDWF
demonstrates a remarkably slower decay of signals with increasing quark
separations. This allows us to access the non-perturbative CS kernel up to
transverse separations of 1 fm. For small transverse separations, our results
agree well with perturbative predictions. At larger transverse separations, our
non-perturbative CS kernel clearly favors certain global fits.
