2022 Meeting on Lattice Parton Physics from Large Momentum Effective Theory (LaMET2022)

Resumming Quark's Longitudinal Momentum Logarithms in LaMET Expansion of Lattice PDFs

Dec 1, 2022, 12:00 PM

25m

Room 8209 (DePaul Center)

Session II

Speaker

Yushan Su (University of Maryland)

Description

In the large-momentum expansion for parton distribution functions (PDFs), the natural physics scale is the longitudinal momentum ($p_z$) of the quarks (or gluons) in a large-momentum hadron. We show how to expose this scale dependence through resumming logarithms of the type ${\ln }^n{p}_z/\mu$ in the matching coefficient, where $\mu$ is a fixed renormalization scale. The result enhances the accuracy of the expansion at moderate $p_z>1$~GeV, and at the same time, clearly shows that the partons cannot be approximated from quarks with $p_z\sim {\mathrm{\Lambda }}_{\mathrm{Q}\mathrm{C}\mathrm{D}}$ which are not predominantly
collinear with the parent hadron momentum, consistent with power counting of the large-momentum effective theory. The same physics mechanism constrains the coordinate space expansion at large distances $z$, the conjugate of $p_z$,
as illustrated in the example of fitting the moments of the PDFs.

Presentation materials

RGR_LaMET2022_V4_Yushan_Su.pdf