Proton Isovector Helicity Distribution on the Lattice at Physical Pion Mass

Lin, Huey‐Wen; Chen, Jiunn-Wei; Ji, Xiangdong; Jin, Luchang; Li, Ruizi; Liu, Yusheng; Yang, Yi-Bo; Zhang, Jianhui; Zhao, Yong

doi:10.1103/physrevlett.121.242003

Cited by 107 publications

(88 citation statements)

References 44 publications

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“…For the calculation in Ref. 27, only one lattice spacing was used and the perturbative matching was at one-loop order, so there are still remnant p R z and µ R dependence after all the systematic corrections. Therefore, p R z = 2.2 GeV, µ R = 3.7 GeV were chosen as central values, while the uncertainty from the remnant p R z and µ R dependence was estimated by the variation of p R z and µ R with the available data and included in the final result.…”

Section: Selected Lattice Resultsmentioning

confidence: 99%

Unraveling high-energy hadron structures with lattice QCD

Zhao

2018

Int. J. Mod. Phys. A

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Parton distribution functions are key quantities for us to understand the hadronic structures in high-energy scattering, but they are difficult to calculate from lattice QCD. Recent years have seen fast development of the large-momentum effective theory which allows extraction of the x-dependence of parton distribution functions from a quasiparton distribution function that can be directly calculated on lattice. The extraction is based on a factorization formula for the quasi-parton distribution function that has been derived rigorously in perturbation theory. A systematic procedure that includes renormalization, perturbative matching, and power corrections has been established to calculate parton distribution functions. Latest progress from lattice QCD has shown promising signs that it will become an effective tool for calculating parton physics.

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Section: Selected Lattice Resultsmentioning

confidence: 99%

Unraveling high-energy hadron structures with lattice QCD

Zhao

2018

Int. J. Mod. Phys. A

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“…A coordinate-space method for the calculation of light-cone distribution amplitudes has also been employed [35]. Significant achievements in the lattice QCD implementations of these approaches have been made in recent years [36][37][38][39][40]. References to many other lattice QCD calculations, the current status and challenges for a meaningful comparison of these lattice calculations with the global fits of PDFs can be found in Refs.…”

Section: Introductionmentioning

confidence: 99%

Pion valence quark distribution from matrix element calculated in lattice QCD

et al. 2019

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We present the first exploratory lattice QCD calculation of the pion valence quark distribution extracted from spatially separated current-current correlations in coordinate space. We show that an antisymmetric combination of vector and axial-vector currents provides direct information on the pion valence quark distribution. Using the collinear factorization approach, we calculate the perturbative tree-level kernel for this current combination and extract the pion valence distribution. The main goal of this article is to demonstrate the efficacy of this general lattice QCD approach in the reliable extraction of parton distributions. With controllable power corrections and a good understanding of the lattice systematics, this method has the potential to serve as a complementary to the many efforts to extract parton distributions in global analyses from experimentally measured cross sections. We perform our calculation on an ensemble of 2+1 flavor QCD using the isotropicclover fermion action, with lattice dimensions 32 3 × 96 at a lattice spacing a = 0.127 fm and the quark mass equivalent to a pion mass mπ 416 MeV.

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“…Recently, significant progress has been made on various aspects of the LaMET procedure, including the renormalization and matching [43, of the quasi-PDF, the power corrections [73][74][75], as well as the lattice calculation of the x-dependence of PDFs and distribution amplitudes [62,73,[76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91]. Notably, the most recent lattice results at physical pion mass [84,85,87,89,91] and large nucleon momenta [85,89,91] have shown encouraging signs that the LaMET approach can lead to a precise determination of the PDFs.…”

Section: Introductionmentioning

confidence: 99%

Towards quasi-transverse momentum dependent PDFs computable on the lattice

Ebert

Stewart

Zhao

2019

J. High Energ. Phys.

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106

182

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Transverse momentum dependent parton distributions (TMDPDFs) which appear in factorized cross sections involve infinite Wilson lines with edges on or close to the light-cone. Since these TMDPDFs are not directly calculable with a Euclidean path integral in lattice QCD, we study the construction of quasi-TMDPDFs with finite-length spacelike Wilson lines that are amenable to such calculations. We define an infrared consistency test to determine which quasi-TMDPDF definitions are related to the TMDPDF, by carrying out a one-loop study of infrared logarithms of transverse position b T ∼ Λ −1 QCD , which must agree between them. This agreement is a necessary condition for the two quantities to be related by perturbative matching. TMDPDFs necessarily involve combining a hadron matrix element, which nominally depends on a single light-cone direction, with soft matrix elements that necessarily depend on two light-cone directions. We show at one loop that the simplest definitions of the quasi hadron matrix element, the quasi soft matrix element, and the resulting quasi-TMDPDF all fail the infrared consistency test. Ratios of impact parameter quasi-TMDPDFs still provide nontrivial information about the TMDPDFs, and are more robust since the soft matrix elements cancel. We show at one loop that such quasi ratios can be matched to ratios of the corresponding TMDPDFs. We also introduce a modified "bent" quasi soft matrix element which yields a quasi-TMDPDF that passes the consistency test with the TMDPDF at one loop, and discuss potential issues at higher orders.

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Proton Isovector Helicity Distribution on the Lattice at Physical Pion Mass

Cited by 107 publications

References 44 publications

Unraveling high-energy hadron structures with lattice QCD

Unraveling high-energy hadron structures with lattice QCD

Pion valence quark distribution from matrix element calculated in lattice QCD

Towards quasi-transverse momentum dependent PDFs computable on the lattice

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