Conveners
Session I
- Xiangdong Ji (University of Maryland, College Park)
Session I
- Peter Petreczky (BNL)
Session I
- Kostas Orginos (College of William and Mary / JLab)
Session I
- Andreas Schafer (Regensburg University)
We will present new results of the proton unpolarized and helicity GPDs, within lattice QCD. Their x-dependence is extracted using the quasi-distribution method, which requires matrix elements of moving hadrons coupled with non-local operators. We use momentum boost up to 1.67 GeV, and momentum transfer squared up to 1 GeV^2. The calculation is performed on an Nf=2+1+1 ensemble of twisted mass...
I present the derivation of the factorization theorem for the quasi-transverse-momentum-dependent (quasi-TMD) operator, within the soft collinear effective field theory framework. The factorized expression is built from the physical TMD distribution, and a nonperturbative lattice related factor. The lattice related functions cancel in appropriately constructed ratios. These ratios could be...
Recently, a hybrid scheme was proposed by the author and company to renormalize the quasi light-front correlations in the LaMET calculation of the PDFs. The hybrid scheme reduces the systematic uncertainty in the renormalization at distances where the leading-twist expansion or perturbation theory is expected to fail, so that one can have a better-controlled Fourier transform to the momentum...
We present the first next-to-next-to-leading order (NNLO) calculation of quark quasi parton distribution functions (PDFs) in the large momentum effective theory. The nontrivial factorization at this order is established explicitly and the full analytic matching coefficients between the quasi distribution and the lightcone distribution are derived for the first time. We demonstrate...
I explore the explicit relationship between the LaMET and pseudo-PDF approaches to collinear hadron structure in the context of a scalar theory, and demonstrate explicitly their equivalence at one loop in perturbation theory. Scalar field theory removes complications associated with gauge theories that enable complete calculations of all quantities, such as the Ioffe-time distribution at...
We present how partonic structure of hadrons can be extracted from matrix elements of two spatially-separated currents, which are computable directly in lattice QCD and can be factorized into parton distribution functions with calculable hard coefficients. We demonstrate the recently derived one-loop matching coefficient has a well-controlled behavior in Ioffe-time, for example, in a specific...
In this presentation, we focus on the pseudo-PDF method of calculating parton distributions. We use a Euclidean space matrix element, called the Ioffe-time pseudo distribution, and Short Distance Factorization, which allows data from all momenta to contribute in the analysis, to obtain parton distributions. We present the latest lattice results from the HadStruc collaboration, discuss several...
We present the first lattice QCD computation of the light quarks and strange helicity PDFs. We used a $N_f=2+1+1$ lattice ensemble generated by the Extended Twisted Mass collaboration (ETMC), with pion mass $M_\pi\approx 250\;{\rm GeV}$, $M_\pi L \approx 3.8$ and lattice spacing $a= 0.0938(2)(3)\;\;{\rm fm}$. Momentum smearing is employed in order to improve the signal-to-noise ratio,...
The transverse-momentum-dependent (TMD) soft function is a key ingredient in QCD factorization of Drell-Yan and other processes with relatively small transverse momentum. We present a lattice QCD study of this function at moderately large rapidity on a 2+1 flavor CLS dynamic ensemble with $a=0.098$ fm. We extract the rapidity-independent (or intrinsic) part of the soft function through a...
The perturbative procedure of matching within Large Momentum Effective Theory connects the quasi-parton distributions to the light-cone distributions that enter physical processes. This procedure has demonstrated success in the extraction of the twist-2 PDFs from lattice QCD. We explore the formalism of matching, for the first time, for the twist-3 PDFs $g_T(x)$, $e(x)$ and $h_L(x)$. We make...
