Parton distribution functions (PDFs) at large $x$ are difficult to be extracted from experimental data, but are extremely important in understanding hadron structures as well as searching for new physics beyond the Standard Model. We study the large $x$ PDFs under the framework of large momentum $P^z$ expansion of lattice quasi-PDFs. In the threshold limit, the matching kernel of quasi-PDF can...
We calculate the leading-twist light-cone distribution amplitude (LCDA) moments of mesons on MILC ensembles using the hyp-smeared clover action. For pseudoscalar mesons, we compute the first moments of the $K$ meson and the second moments of the $\pi$ and $K$ mesons. For vector mesons, we compute the first moments of the $K^{*}$ meson and the second moments of the $\rho$, $K^{*}$, and $\phi$ mesons.
I will present the recent lattice calculation of the unpolarized generalized form factors by the Hadtruc collaboration. We use the pseudo-distribution formalism with an extended kinematic domain in $(\xi, t)$. I will discuss the limitations and improvement perspectives of this study.
We present the first lattice QCD calculation of the rapidity anomalous dimension of transverse-momentum-dependent distributions (TMDs), i.e. the Collins-Soper (CS) kernel, employing the recently proposed Coulomb-gauge-fixed quasi-TMD formalism as well as a chiral-symmetry-preserving lattice discretization. This unitary lattice calculation is conducted using the domain wall fermion...
The TMD soft function may be obtained by formulating the Wilson line in terms of auxiliary 1-dimensional fermion fields on the lattice. We take inspiration from heavy quark effective theory (HQET) in order to define the auxiliary field. Our computation takes place in the region of the lattice that corresponds to the “spacelike” region in Minkowski space in order to obtain the Collins soft...
In this talk I revisit the time-ordering issue of TMD soft factors based on coordinate-space analyticity properties of Wightman functions in Wightman-Osterwalder-Schrader QFTs.
In particular, I show that the TMD soft factor for the DY process in three rapidity regularization schemes can be smoothly connected to each other in a way that maintain certain crucial (S=S_t type) equalities...
Off-lightcone Wilson-line operators are constructed using local operators connected by time-like or space-like Wilson lines, which ensure gauge invariance. Off-lightcone Wilson-line operators have broad applications in various contexts. For instance, space-like Wilson-line operators play a crucial role in determining quasi-distribution functions (quasi-PDFs), while time-like Wilson-line...
We discuss a general framework for the evaluation of the parton distribution, distribution amplitudes as well as the form factors in light hadrons in the QCD vacuum. At medium resolution of the order of the inverse mean instanton size, the glue is mostly localized in single or pair of pseudoparticles, and globally constrained by the fluctuations of their topological charges. These...
We analyze the gauge fixing precision dependence of some non-local quark-blinear lattice operators interesting in computing parton physics for several measurements, using 5 lattice spacings ranging from 0.032 fm to 0.121 fm. Our results show that gauge dependent non-local measurements are significantly more sensitive to the precision of gauge fixing than anticipated. The impact of imprecise...
Recently, it is proposed to compute Parton distribution in fixed Coulomb gauge without Wilson line, which could greatly improve the efficiency of lattice calculations. However, there are some concerns about the systematic uncertainties from Gribov copies, which correspond to the ambiguity in the nonperturbative gauge fixing, is not controlled. This work gives an assessment on the systematic...
Momentum distributions of quarks/gluons inside a light baryon in a hard exclusive process are encoded in the light-cone distribution amplitudes (LCDAs). In this work, we point out that the leading twist LCDAs of a light baryon can be obtained through a simulation of a quasi-distribution amplitude calculable on lattice QCD within the framework of the large-momentum effective theory. We...
In this talk, I'll report our earlier work on the factorization of quasi GPD based on collinear expansion. Using ward identity and BRST symmetry, we show how to get a gauge-invariant factorization form. We also discuss the inconsistency of the mixing channel results in literature: its origin and possible solutions.
We compute the matching kernel of singlet quasi-parton distributions in the hybrid ratio scheme. Momentum conservation of the quasi-distributions is observed. However, the renormalization condition is complicated by the quark and gluon mixing.
We present the first attempt at using the hybrid-ratio renormalization scheme on gluon quasi-lightfront correlators from lattice quantum chromodynamics with $a \approx 0.12$ fm at pion masses $M_\pi \approx 310$ and $690$ MeV. We measured over 1.2 million two-point correlators and used momentum smearing and aggressive gauge link smearing for the gluon operator to obtain a reasonable level of...
