Predicting the light-front holographic TMDs of the pion

Abstract

We predict the twist-2 Transverse Momentum Dependent parton distribution functions (TMDs) of the pion, namely the unpolarized quark TMD, $f_1(x,k_{\perp })$, and the transversely polarized quark TMD, also known as the Boer-Mulders function, $h_1^{\perp }(x,k_{\perp })$, using a holographic light-front pion wavefunction with dynamical spin effects. These spin effects, in conjunction with gluon rescattering, are crucial to predict a non-zero holographic Boer-Mulders function. We investigate the use of a non-perturbative SU(3) gluon rescattering kernel, thus going beyond the usual approximation of perturbative U(1) gluons. We find that the non-perturbative color dynamics offer a more promising way to describe the available lattice data on the generalized Boer-Mulders shifts.

Comments: 20 pages, 4 figures