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Title: Parton distributions and lattice QCD calculations: A community white paper

In the framework of quantum chromodynamics (QCD), parton distribution functions (PDFs) quantify how the momentum and spin of a hadron are divided among its quark and gluon constituents. Two main approaches exist to determine PDFs. The first approach, based on QCD factorization theorems, realizes a QCD analysis of a suitable set of hard-scattering measurements, often using a variety of hadronic observables. The second approach, based on first-principle operator definitions of PDFs, uses lattice QCD to compute directly some PDF-related quantities, such as their moments. Motivated by recent progress in both approaches, in this paper we present an overview of lattice-QCD and global-analysis techniques used to determine unpolarized and polarized proton PDFs and their moments. We provide benchmark numbers to validate present and future lattice-QCD calculations and we illustrate how they could be used to reduce the PDF uncertainties in current unpolarized and polarized global analyses. Finally, this document represents a first step towards establishing a common language between the two communities, to foster dialogue and to further improve our knowledge of PDFs.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;  [15] ;  [16] ;  [17] ;  [18] ;  [19] more »;  [20] ;  [21] ;  [22] ;  [3] ;  [23] ;  [24] ;  [25] ;  [26] ;  [27] ;  [28] ;  [29] ;  [30] « less
  1. Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy. Dept. of Computational Mathematics
  2. Univ. of Oxford (United Kingdom). Rudolf Peierls Centre for Theoretical Physics; Univ. of Edinburgh, Scotland (United Kingdom). Higgs Centre for Theoretical Physics. School of Physics and Astronomy
  3. Southern Methodist Univ., Dallas, TX (United States). Dept. of Physics
  4. College of William and Mary, Williamsburg, VA (United States). Physics Dept.; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  5. Vrije Univ. (VU), Amsterdam (Netherlands). Dept. of Physics and Astronomy; Nikhef, Amsterdam (Netherlands)
  6. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hampton Univ., Hampton, VA (United States)
  7. Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; The Cyprus Inst., Nicosia (Cyprus). Computation-based Science and Technology Research
  8. Univ. of Pavia (Italy). Dept. of Physics; National Inst. of Nuclear Physics (INFN), Pavia (Italy)
  9. National Taiwan Univ., Taipei (Taiwan). Dept. of Physics. Center for Theoretical Sciences. Leung Center for Cosmology and Particle Astrophysics
  10. Univ. of Regensburg (Germany). Inst. for Theoretical Physics
  11. Univ. of Oxford (United Kingdom). Dept. of Physics
  12. Temple Univ., Philadelphia, PA (United States). Dept. of Physics
  13. Univ. of Edinburgh, Scotland (United Kingdom). Higgs Centre for Theoretical Physics. School of Physics and Astronomy
  14. New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics
  15. Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. for Computing (NIC)
  16. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  17. Univ. of Oxford (United Kingdom). Rudolf Peierls Centre for Theoretical Physics; Univ. College London (United Kingdom). Dept. of Physics and Astronomy
  18. Shanghai Jiao Tong Univ. (China). T. D. Lee Inst.
  19. Polish Academy of Sciences, Krakow (Poland). Inst. of Nuclear Physics
  20. Univ. of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy
  21. Univ. of Virginia, Charlottesville, VA (United States). Physics Dept.; National Inst. of Nuclear Physics (INFN), Frascati (Italy). National Lab. of Frascati
  22. Univ. of Washington, Seattle, WA (United States). Inst. for Nuclear Theory
  23. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  24. Univ. Grenoble-Alpes, Grenoble (France). Lab. of Subatomic Physics and Cosmology
  25. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
  26. Univ. College London (United Kingdom). Dept. of Physics and Astronomy
  27. Tubingen Univ. (Germany). Inst. for Theoretical Physics
  28. Johannes Gutenberg Univ., Mainz (Germany). PRISMA Cluster of Excellence. Inst. for Nuclear Physics
  29. Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy
  30. Univ. of Adelaide, SA (Australia). Special Research Centre for the Subatomic Structure of Matter (CSSM). Dept. of Physics
Publication Date:
Report Number(s):
JLAB-THY-17-2604; DOE/OR/23177-4281; arXiv:1711.07916
Journal ID: ISSN 0146-6410; PII: S0146641018300073
Grant/Contract Number:
AC05-06OR23177; FG02-00ER41132; FG02-04ER41302; SC0010129; SC0008791; FG02-96ER40965; SC0016286
Type:
Accepted Manuscript
Journal Name:
Progress in Particle and Nuclear Physics
Additional Journal Information:
Journal Volume: 100; Journal ID: ISSN 0146-6410
Publisher:
Elsevier
Research Org:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Univ. of Washington, Seattle, WA (United States); College of William and Mary, Williamsburg, VA (United States); Southern Methodist Univ., Dallas, TX (United States); Hampton Univ., Hampton, VA (United States); New Mexico State Univ., Las Cruces, NM (United States); Univ. of Virginia, Charlottesville, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); BNL Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; lattice QCD; global QCD fits; unpolarized/polarized parton distribution functions (PDFs)
OSTI Identifier:
1433816