Conveners
Session II
- Peter Petreczky (BNL)
Session II
- David Richards (Jefferson Lab)
Session II
- Andreas Schaefer (Regensburg University)
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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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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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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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