Login
LFQCD Seminar

QCD Vacuum-Based Framework for Light-Front Dynamics and Parton Structure

by Prof. Weiyang Liu (Stony Brook U)

→ Asia/Shanghai
Description

At Bjorken limit, light-cone correlators dominate hadron structure in high-energy collisions. Light-front dynamics (LFD) thus provides a natural language describing hadron structure in terms of partonic degrees of freedom. However, direct light-front quantization (LFQ) leads to severe infrared singularities induced by zero modes. These divergences reflect the absence of an intrinsic IR scale and nontrivial vacuum structure, thus placing QCD at a kinematical critical point. As a result, a well-defined partonic description requires the infrared vacuum structure to be properly renormalized and clearly specified before taking the infinite-momentum limit. To address this, we model the QCD vacuum using instanton liquid ensemble (ILE). In ILE, nonlocal interactions for light quarks emerge from semiclassical gauge field configurations in Euclidean space. By analytical continuation back to light-cone signature, QCD vacuum-based wave functions obtained by Bethe-Salpeter-Faddeev equation can be connected to light-front wave functions. This framework allows one to construct parton observables, including distribution amplitudes (DAs), parton distribution functions (PDFs), and transverse-momentum-dependent distributions (TMDs) for light mesons and nucleons from QCD vacuum at a medium renormalization scale. To connect these mid-resolution quantities to high-energy phenomenology, the appropriate renormalization-group evolution must be implemented, including ERBL, DGLAP, and CSS evolution, which can also can be calculated within the same ILE framework in a self-contained manner. The results show good agreement with global analysis and lattice QCD calculations. Therefore, we provide a promising framework for reliable predictions for future measurements and a clean picture in which light-front parton structure emerges from topological QCD vacuum, bridging nonperturbative vacuum physics with measurable partonic observables.

 

=============

https://zoom.us/j/98684504208?pwd=colk7PaQUv7btR4t0uAFs6Nnaf34l5.1

ZOOM ID: 986 8450 4208
PW: 488530