Selected results on hadron structure using state-of-the-art lattice QCD simulations
Constantia Alexandrou
TL;DR
The paper surveys lattice QCD studies of hadron structure using simulations at near-physical parameters. It outlines a program computing hadron masses, the nucleon axial charge $g_A$, gluon and quark unpolarized moments including $\langle x \rangle$ and $\langle x \rangle_g$, and generalized parton distributions via twist-two operators such as $O_V^a$, $O_A^a$, and $O_T^a$, with $A_{20}$, $B_{20}$, and $C_{20}$ form factors. It reports that at the physical point $g_A$ agrees with experiment, quantifies SU(3) breaking with $\delta_{\rm SU(3)} \approx 0.10$--$0.15$ for octet baryons, and presents a spin decomposition $J^q=\tfrac{1}{2}[A_{20}^q(0)+B_{20}^q(0)]$ including disconnected contributions; it also explores direct quasi-PDF approaches and the associated renormalization/matching challenges. It demonstrates lattice QCD's reliability for hadron structure and points to rapid progress toward PDFs and ab initio nuclear physics as systematics are controlled ($a$, $L$, excited-state effects, and renormalization).
Abstract
We review progress on hadron structure using lattice QCD simulations at or near to physical values of the QCD parameters. In particular, we discuss recent results on hadron masses, the nucleon charges, spin, gluon and quark unpolarized moments, the axial charge of hyperons, and the pion unpolarized moment.