Abstract
The strong force which binds hadrons is described by the theory of quantum chromodynamics (QCD). Determining the character and manifestations of QCD is one of the most important and challenging outstanding issues necessary for a comprehensive understanding of the structure of hadrons. Within the context of the QCD parton picture, the parton distribution functions (PDFs) have been remarkably successful in describing a wide variety of processes. However, these PDFs have generally been confined to the description of collinear partons within the hadron. New experiments and facilities provide the opportunity to additionally explore the transverse structure of hadrons which is described by generalized parton distributions (GPDs) and transverse-momentum-dependent parton distribution functions (TMD PDFs). In our previous report Lin et al. (2018), we compared and contrasted the two main approaches used to determine the collinear PDFs: the first based on perturbative QCD factorization theorems, and the second based on lattice-QCD calculations. In the present report, we provide an update of recent progress on the collinear PDFs, and also expand the scope to encompass the generalized PDFs (GPDs and TMD PDFs). We review the current state of the various calculations, and consider what new data might be available in the near future. We also examine how a shared effort can foster dialog between the PDF and lattice-QCD communities, and yield improvements for these generalized PDFs.
| Original language | English |
|---|---|
| Article number | 103908 |
| Journal | Progress in Particle and Nuclear Physics |
| Volume | 121 |
| DOIs | |
| State | Published - Nov 2021 |
Bibliographical note
Publisher Copyright:© 2021 Elsevier B.V.
Funding
We are grateful to Autumn Hewitt, Nicole Kokx and Brenda Wenzlick, for their help in the organization of the workshop. The workshop was partly supported by Michigan State University, USA and US National Science Foundation via the grant under PHY 1653405 ?CAREER: Constraining Parton Distribution Functions for New-Physics Searches?. We thank Kostas Orginos for his early-stage involvement in organizing the workshop, Alberto Accardi, Jorge Benel, Nikhil Karthik, Zhouyou Fan, Paul Reimer, Dave Soper, Michael Wagman, Zhite Yu for their participation and discussions during the PDFLattice2019 workshop, and Xiangdong Ji for a critical reading of the manuscript. We thank Joseph Karpie and Gunnar Bali for providing numbers for Figs. 7 and 22, respectively, and Phiala Shanahan for remaking Fig. 33 for this paper. We thank H. Moutarde, Ingo Schienbein, P. Sznajder, and Yong Zhao as well as members of the Lattice Hadron Physics Collaboration (LHPC) and the Lattice TMD Collaboration for useful discussion during the preparation of this report. We are pleased to acknowledge support from: the U.S. Department of Energy, grants DE-SC0020405 [M. Constantinou], DE-SC0011090 [M. Ebert], DE-FG02-96ER40965 [M. Engelhardt]; DE-SC0010129 [T. Hobbs, F. Olness, P. Nadolsky], DE-SC0016286 [S. Liuti], DE-AC05-06OR23177 [J.W. Qiu], DE-FG02-97ER41028 [A. Radyushkin], DE-SC0012704 [A. Rajan], DE-SC0018106 [T. C. Rogers], and the DOE Topical Collaboration on TMDs, USA [M. Engelhardt, J.W. Qiu]; Jefferson Science Associates, USA, LLC under U.S. DOE Contract DE-AC05-06OR23177 [J.W. Qiu, A. Radyushkin, T.C. Rogers]; the US National Science Foundation grants PHY-1714407 [M. Constantinou], PHY 1653405 [H. Lin, R. Zhang], PHY-1719914 [C. Yuan]; the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program grant agreement N.647981, 3DSPIN [M. Radici], grant agreement N. 824093 [C. Mezrag], and the Marie Sklodowska-Curie Action grant agreement N. 752748, ParDHonS [E. Nocera]; the Universidad Nacional Aut?noma de M?xico grant DGAPA-PAPIIT IA101720 [A. Courtoy]; the Scottish Funding Council, United Kingdom grant H14027 [T. Giani]; the Narodowe Centrum Nauki, Poland grant DEC-2017/27/B/ST2/01985 [K. Kutak]; the Kosciuszko Foundation, USA [A. Kusina]; the Research Corporation for Science Advancement, USA through the Cottrell Scholar Award [H. Lin]; the Alexander von Humboldt Foundation, Germany through a Feodor Lynen Research Fellowship [M. Ebert]; and the National Natural Science Foundation of China (Grant No. 11975051, 12061131006) and Fundamental Research Funds for the Central Universities, China [J. Zhang]; the JLab EIC Center, USA through an EIC Center Fellowship [T. Hobbs]; the Wu-Ki Tung, USA endowed chair in particle physics [C. Yuan]; and the LDRD program of Brookhaven National Laboratory, USA [A. Rajan]. We are pleased to acknowledge support from: the U.S. Department of Energy , grants DE-SC0020405 [M. Constantinou], DE-SC0011090 [M. Ebert], DE-FG02-96ER40965 [M. Engelhardt]; DE-SC0010129 [T. Hobbs, F. Olness, P. Nadolsky], DE-SC0016286 [S. Liuti], DE-AC05-06OR23177 [J.W. Qiu], DE-FG02-97ER41028 [A. Radyushkin], DE-SC0012704 [A. Rajan], DE-SC0018106 [T. C. Rogers], and the DOE Topical Collaboration on TMDs, USA [M. Engelhardt, J.W. Qiu]; Jefferson Science Associates, USA , LLC under U.S. DOE Contract DE-AC05-06OR23177 [J.W. Qiu, A. Radyushkin, T.C. Rogers]; the US National Science Foundation grants PHY-1714407 [M. Constantinou], PHY 1653405 [H. Lin, R. Zhang], PHY-1719914 [C. Yuan]; the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program grant agreement N.647981 , 3DSPIN [M. Radici], grant agreement N. 824093 [C. Mezrag], and the Marie Sklodowska-Curie Action grant agreement N. 752748 , ParDHonS [E. Nocera]; the Universidad Nacional Autónoma de México grant DGAPA-PAPIIT IA101720 [A. Courtoy]; the Scottish Funding Council, United Kingdom grant H14027 [T. Giani]; the Narodowe Centrum Nauki, Poland grant DEC-2017/27/B/ST2/01985 [K. Kutak]; the Kosciuszko Foundation, USA [A. Kusina]; the Research Corporation for Science Advancement, USA through the Cottrell Scholar Award [H. Lin]; the Alexander von Humboldt Foundation, Germany through a Feodor Lynen Research Fellowship [M. Ebert]; and the National Natural Science Foundation of China (Grant No. 11975051 , 12061131006 ) and Fundamental Research Funds for the Central Universities, China [J. Zhang]; the JLab EIC Center, USA through an EIC Center Fellowship [T. Hobbs]; the Wu-Ki Tung, USA endowed chair in particle physics [C. Yuan]; and the LDRD program of Brookhaven National Laboratory, USA [A. Rajan].
| Funders | Funder number |
|---|---|
| Michigan State University | |
| DOE Topical Collaboration on TMDs | |
| Joseph Karpie and Gunnar Bali | |
| Research Corporation for Science Advancement | |
| Jefferson Science Associates | |
| European Commission | |
| Kosciuszko Foundation | |
| Laboratory Directed Research and Development | |
| H2020 European Research Council | |
| JLab EIC Center | |
| Brookhaven National Laboratory (BNL) | |
| Fundamental Research Funds for the Central Universities | |
| Alexander von Humboldt-Stiftung | |
| National Science Foundation Arctic Social Science Program | PHY-1714407, PHY-1719914, PHY 1653405 |
| U.S. Department of Energy EPSCoR | DE-SC0011090, DE-SC0016286, DE-SC0010129, DE-SC0012704, DE-SC0018106, DE-SC0020405, DE-FG02-97ER41028, DE-AC05-06OR23177, DE-FG02-96ER40965 |
| Universidad Nacional Autónoma de México | DGAPA-PAPIIT IA101720 |
| National Natural Science Foundation of China (NSFC) | 12061131006, 11975051 |
| Fundação para a Ciência e Tecnologia I.P. | PTDC/CCI-BIO/29266/2017 |
| Narodowe Centrum Nauki, Poland | DEC-2017/27/B/ST2/01985 |
| Scottish Funding Council, United Kingdom | H14027 |
| Horizon 2020 Framework Programme | 647981, 824093, 3DSPIN |
| H2020 Marie Skłodowska-Curie Actions | 752748 |
Keywords
- Generalized Parton Distributions (GPD)
- Global QCD fits
- Lattice QCD
- Transverse Momentum Dependent PDFs (TMD PDFs)
- Unpolarized/polarized parton distribution functions (PDFs)
ASJC Scopus subject areas
- Nuclear and High Energy Physics