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19. Lattice QCD Determination of the Bjorken-$x$ Dependence of PDFs at Next-to-next-to-leading OrderYong Zhao07/12/2021, 08:30
In this talk, we present a direct calculation of the $x$-dependence of pion valence PDF with the large-momentum effective theory approach. In this calculation we adopt the most up-to-date theoretical developments on the systematic corrections, which include the hybrid renormalization scheme that rigorously renormalizes the lattice matrix elements at both short and long distances, as well as...
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Xiang Gao (BNL&CCNU)07/12/2021, 08:55
We present the first lattice calculation of pion valence parton distribution using matching formula at NNLO level. We use the Wilson-Clover fermion on three 2+1 flavor HISQ ensembles of lattice spacings a = 0.04, 0.06 and 0.076 fm, with two pion mass including the physical one. Two unitary Domain-Wall calculations at physical point are also presented. This allows us to control the continuum...
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Yushan Su (University of Maryland)07/12/2021, 09:15
Large-momentum effective theory provides a way to extract the parton physics from lattice data based on first-principle calculation. In applying large-momentum effective theory, renormalization of
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the Euclidean correlators in lattice regularization is a challenge due to
linear divergences in the self-energy of Wilson lines. We will give a review on different renormalization methods to deal... -
Jiunn-Wei Chen07/12/2021, 09:35
I would like to talk about some unrelated topics in LaMET, including the renormalon effect, applying Chiral Perturbation Theory to quasi-PDFs, and the matching kernels for the hybrid renormalization and self-renormalization.
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Joseph Karpie07/12/2021, 10:25
The continuum limit is a fundamental step when using a lattice regulator and necessary for any high precision calculation using lattice QCD. The matrix elements used in determining a PDF have two dimensionful parameters, compared to the 0 or 1 of most lattice calculations, which significantly complicates the continuum limit extrapolation. In this presentation, I will describe a method which...
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Colin Egerer (Jefferson Lab)07/12/2021, 10:50
We apply the Distillation spatial smearing program to the extraction of the
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unpolarized isovector valence PDF of the nucleon using the pseudo-distribution formalism. The improved volume sampling and control of excited-states afforded by distillation leads to a dramatically improved determination of the requisite Ioffe-time Pseudo-distribution (pITD).
The valence PDF is extracted by analyzing... -
Anthony Grebe07/12/2021, 11:15
The pion light-cone distribution amplitude (LCDA) carries information about the momentum distribution of its quarks, which is an important input to various experiments. We present a proof-of-concept lattice calculation of the second Mellin moment of the pion LCDA as the first numerical implementation of the heavy-quark operator product expansion (HOPE) method. The resulting value for the...
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Robert Perry (National Yang Ming Chiao Tung University)07/12/2021, 11:30
The light-cone distribution amplitude (LCDA) is a key object of interest in a range of high-energy, exclusive processes in QCD. In this talk, we describe the application of the heavy quark operator product expansion (HOPE) method to a preliminary study of the fourth Mellin moment of the pion LCDA. This constitutes the first study of the fourth moment from lattice QCD. We present an exploratory...
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Patrick Barry07/12/2021, 11:45
For the first time, we perform a fit of pion parton distribution functions (PDFs) to reduced pseudo Ioffe time distributions and current-current correlator "good lattice cross sections" generated from lattice QCD simultaneously with experimental data. We make use of the factorization formulas convoluting the matching coefficients with the valence quark distribution to fit to real components...
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Jinchen He08/12/2021, 08:30
We present the state-of-the-art lattice QCD calculation of the light-cone distribution amplitudes (DAs) of pion and kaon using large-momentum effective theory. The calculation is done at three lattice spacings $a\approx\{0.06,0.09,0.12\}$~fm and physical pion and kaon masses, with the meson momenta $P_z = \{1.29,1.72,2.15\}$ GeV. The result is non-perturbatively renormalized in a recently...
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Jun Hua08/12/2021, 08:55
We present the first lattice QCD calculation of the distribution amplitudes of longitudinally and transversely polarized vector mesons K∗ and φ using large momentum effective theory. We use the clover fermion action on three ensembles with 2+1+1 flavors of highly improved staggered quarks (HISQ) action, generated by MILC collaboration, at physical pion mass and {0.06, 0.09, 0.12} fm lattice...
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Nikhil Karthik08/12/2021, 09:15
I will present some recent results from the HadStruc collaboration on the extraction of transversity PDF of the proton by using fits to NLO leading-twist OPE. I will explain how the systematic errors are taken care of, and then present the x-dependence of the transversity PDF and its comparison with recent JAM global fit results.
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Fei Yao08/12/2021, 09:40
In this talk, I present some updated results on nucleon transversity parton distribution function (PDF) from lattice QCD using large-momentum effective theory. The calculation is done with three lattice spacings, 0.086, 0.064 and 0.049 fm. The bare matrix elements are nonperturbatively renormalized in a recently proposed hybrid scheme. Also a continuum extrapolation is performed. Our results...
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Wayne Morris08/12/2021, 10:35
We present the results that are necessary in the ongoing lattice calculations of the polarized gluon parton distribution functions within the pseudo-PDF approach. We give a classification of possible two-gluon correlator functions and identify those that contain the invariant amplitude determining the polarized gluon PDF in the light-cone $z^2 \to 0$ limit. One-loop calculations have been...
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Zhouyou Fan08/12/2021, 10:55
We present the $x$-dependent nucleon and pion gluon distribution from lattice QCD using the pseudo-PDF approach, on lattice ensembles with $2+1+1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. We use clover fermions for the valence action and momentum smearing to achieve pion boost momentum up to 2.56~GeV on three lattice spacings $a\approx 0.9, 0.12$ and...
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Raza Sufian08/12/2021, 11:15
We present lattice QCD calculation of unpolarized and polarized gluon Ioffe-time distributions using the pseudo-PDFs approach. We construct the nucleon interpolation fields using the distillation technique and smear the gauge fields using gradient flow. We calculate flow time-independent reduced Ioffe-time pseudo-distribution and from that, determine the unpolarized gluon PDF in the...
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Shuai Zhao (Old Dominion University/Jefferson Lab)08/12/2021, 11:40
We present the results for the one-loop corrections to the "gluon condensate" twist-4 PDF F(x), in particular, we give expression for the $gg$-part of its evolution kernel. To enforce strict compliance with the gauge invariance requirements, we have used on-shell states for external gluons and have obtained identical results both in Feynman and light-cone gauges. No "zero mode" terms were...
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Yizhuang Liu (Jagiellonian University)09/12/2021, 08:30
Light-front wave functions play a fundamental role in the light-front quantization approach to QCD and hadron structure. However, a naive implementation of the light-front quantization suffers from various subtleties including the well-known zero-mode problem such as the associated rapidity divergences as well as breaking of spatial rotational symmetry. In the talk, I will show that the...
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Min-Huan Chu (Shanghai Jiao Tong University)09/12/2021, 08:55
In this work we present the transversity $b_{\perp}$-dependence Collins-Soper kernel extracted from pion transverse momentum dependent wave functions in the framework of large momentum effective theory from lattice QCD. We use clover fermion action with $2 + 1 + 1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. A single ensemble is used, with lattice...
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Michael Wagman09/12/2021, 09:15
I will present a LQCD calculation of the nonperturbative Collins-Soper kernel, which describes the rapidity evolution of quark transverse-momentum-dependent parton distribution functions. The kernel is extracted at transverse momentum scales in the range 400 MeV < qT < 1.7 GeV in a calculation with dynamical fermions and quark masses corresponding to a larger-than-physical pion mass of 538...
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Kuan Zhang (Institute of Theoretical Physics，Chinese Academy of Sciences)09/12/2021, 09:40
Non-local operator has linear divergence on lattice. RI/MOM scheme cannot eliminate the linear divergence in quasi-PDF operator, especially for the clover valence quark. Using RI/MOM scheme will undermine the credibility of our results.
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We try to use the square root of Wilson loop to renormalize bare matrix element of TMD-PDF. When calculating TMD-PDF in the rest frame, we found renormalized... -
Zhiquan Sun09/12/2021, 10:35
The extraction of nonperturbative TMD physics is made challenging by prescriptions that shield the Landau pole, which entangle long- and short-distance contributions in momentum space. The use of different prescriptions then makes the comparison of fit results for underlying nonperturbative contributions meaningless on their own. We propose a model-independent method to restrict...
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Aurora Scapellato09/12/2021, 10:55
In this talk we present results for isovector transversity generalized parton distributions (GPDs) of the proton obtained within lattice QCD. We employ the quasi-distribution formalism, which relies on computations of nonlocal matrix elements of boosted hadron states. Large momentum effective theory (LaMET) is then used to match quasi- to light-cone GPDs.
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Results are obtained on an... -
Jack Dodson09/12/2021, 11:20
Calculating the x-dependence of PDFs and GPDs from lattice QCD has become feasible in the last few years due to novel approaches. In the work presented, we employ the quasi-distributions method, which relies on matrix elements of non-local operators, matched to the light-cone distributions using Large Momentum Effective Theory (LaMET). We focus on results for the first-ever lattice QCD...
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Yao Ji09/12/2021, 11:40
In this talk, I will discuss our recent studies of the twist-3 nucleon parton distribution functions suitable for lattice simulations. The corresponding factorized expressions are derived in terms of the twist-two and twist-three collinear distributions to one-loop accuracy. We present the one-loop matching coefficient functions both in position space, as the factorization theorem for...
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Santanu Mondal (Michigan State University)
We present preliminary lattice QCD calculations of the unpolarized and polarized distributions of the strange quark using the LaMET method. We use three $N_f=2+1+1$ HISQ ensembles generated by MILC collaboration at lattice spacings $a \approx 0.09, 0.12 {~\rm and~} 0.15$ fm, and clover valence fermions with two valence pion masses: 310 and 690 MeV. We use momentum-smeared sources to improve...
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