Wilson lines in the operator definition of TMDs : spin degrees of freedom and renormalization
Faculty of Sciences. Physics
, p. 1-5
University of Antwerp
A generalized idea of gauge invariance, that embodies into the Wilson lines the spin-dependent Pauli term ∼Fμν[γμ,γν], is applied to set up a new framework for the operator definition of transverse-momentum-dependent parton densities (TMDs). We show that such a treatment of gauge invariance is justified, since it does not change the leading-twist behavior of the TMDs, albeit it contributes to their twist-three properties, in particular, to their anomalous dimensions. We discuss other consequences of this generalization and its possible applications to lattice simulations of the TMDs.