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Volume 336 - XIII Quark Confinement and the Hadron Spectrum (Confinement2018) - B: Light quarks
Perturbative investigation of "Wilson-line"-type operators in Parton Physics
G. Spanoudes,* H. Panagopoulos
*corresponding author
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Pre-published on: 2019 September 12
Published on: 2019 September 26
We investigate the renormalization of a class of gauge-invariant nonlocal quark bilinear operators, including a finite-length Wilson-line (called Wilson-line operators). The matrix elements of these operators are involved in the recent "quasi-distribution" approach for computing light-cone distributions of Hadronic Physics on the lattice. We consider two classes of Wilson-line operators: straight-line and staple-shaped operators, which are related to the parton distribution functions (PDFs) and transverse momentum-dependent distributions (TMDs), respectively. We present our one-loop results for the conversion factors of straight-line operators between the RI$'$ (appropriate for nonperturbative renormalization on the lattice) and $\overline{MS}$ (typically used in phenomenology) renormalization schemes in the presence of nonzero quark masses. In addition, we present the first results of our preliminary work for the renormalization of staple-shaped operators both in continuum (Dimensional Regularization) and lattice (Wilson/clover fermions and Symanzik improved gluons) regularizations. We identify the observed mixing pairs among these operators, which must be disentangled in the nonperturbative investigations of heavy-quark quasi-PDFs and of light-quark quasi-TMDs.
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