Abstract
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 document 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. 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.
| Original language | English |
|---|---|
| Pages (from-to) | 107-160 |
| Number of pages | 54 |
| Journal | Progress in Particle and Nuclear Physics |
| Volume | 100 |
| Early online date | 31 Jan 2018 |
| DOIs | |
| Publication status | Published - May 2018 |
Bibliographical note
PDF ArXiv: 80 pages, 15 figures, 28 tablesFunding
We are grateful to Jacqueline Gills and Michelle Bosher for their help in the organization of the workshop. We thank Rodolfo Sassot and Jacob Ethier for providing us with the DSSV14 predictions in Table C.3 and with the JAM17 predictions in Tables 3.6 and C.2, C.3 . The workshop was partly supported by the European Research Council (ERC) via the Starting Grant PDF4BSM - Parton Distributions in the Higgs Boson Era . We also thank the Department of Energy’s (DoE) Institute of Nuclear Theory (INT) at the University of Washington in Seattle ( DE-FG02-00ER41132 ) for partial support during the completion of this work. This work was also partially funded by the U.S. DoE contract No. DE-AC05-06OR23177 , under which Jefferson Science Associates, LLC operates Jefferson Lab. H.-W.L. is supported by the U.S. National Science Foundation (NSF) under Grant PHY 1653405 ; E.R.N. by the U.K. Science and Technology Facilities Council (STFC) via the Rutherford Grant ST/M003787/1 and the Consolidated Grant ST/P000630/1 ; K.O. by Jefferson Science Associates, LLC under U.S. DoE contract No. DE-AC05-06OR23177 , by U.S. DoE under Grant No. DE-FG02-04ER41302 , and by STFC via the Consolidated Grant ST/P000681/1 ; F.I.O. and P.M.N. by the U.S. DoE under Grant No. DE-SC0010129 ; J.R. by the ERC via the Starting Grant PDF4BSM - Parton Distributions in the Higgs Boson Era and by the Dutch Organization for Scientific Research (NWO) ( 680-91-105 ); A.A. acknowledges support by the U.S. DoE under contract No. DE-SC008791 ; A.B. and G.B. by the ERC via the Consolidator Grant 3DSPIN - Mapping the proton in 3D ; J.-W.C. partly by the Ministry of Science and Technology, Taiwan , under Grant No. 105-2112-M-002-017-MY3 and the Kenda Foundation ; S.C. by the Deutsche Forschungsgemeinschaft via the SFB/TRR 55 project; M.C. by the U.S. DoE, Office of Science, Office of Nuclear Physics, within the framework of the TMD Topical Collaboration, as well as by the NSF under Grant No. PHY-1714407 ; L.D.D. by the Royal Society , Wolfson Research Merit Award, Grant No. WM140078 : M.E. by the U.S. DoE, Office of Science, Office of Nuclear Physics through Grant DE-FG02-96ER40965 as well as through the TMD Topical Collaboration; L.A.H.-L. and R.S.T. by the STFC via Grant awards ST/L000377/1 and ST/P000274/1 ; S.L. by the U.S. DoE through Grant No. DE-SC0016286 ; C.J.M. by the U.S. DoE through Grant No. DE-FG02-00ER41132 ; T.I. by Science and Technology Commission of Shanghai Municipality (Grants No. 16DZ2260200 ) and in part by the DoE, Laboratory Directed Research and Development (LDRD) funding of BNL, under contract No. DE-EC0012704 ; C.-P.Y. by the NSF under Grant No. PHY-1417326 ; R. G. by the U.S. DoE, Office of Science of High Energy Physics, under Contract No. DE-KA-1401020 . Appendix A
| Funders | Funder number |
|---|---|
| Dutch Organization for Scientific Research | |
| Jefferson Science Associates, LLC | DE-SC0010129, DE-FG02-04ER41302, DE-AC05-06OR23177 |
| Office of Nuclear Physics | PHY-1714407 |
| Office of Science of High Energy Physics | |
| Royal Society , Wolfson Research | DE-FG02-00ER41132, DE-SC0016286, ST/P000274/1, WM140078, DE-FG02-96ER40965 |
| S.C. | |
| T.I. | |
| U.S. DOE | |
| U.S. National Science Foundation | |
| Henry P. Kendall Foundation | |
| Office of Science | |
| Brookhaven National Laboratory | PHY-1417326, DE-EC0012704 |
| Brookhaven National Laboratory | |
| Laboratory Directed Research and Development | |
| Horizon 2020 Framework Programme | 810660, 647981 |
| Horizon 2020 Framework Programme | |
| Science and Technology Facilities Council | ST/P000681/1, ST/M003787/1, ST/L000377/1, ST/P000630/1 |
| Science and Technology Facilities Council | |
| European Research Council | |
| Deutsche Forschungsgemeinschaft | |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | 680-91-105, 3DSPIN, DE-SC008791 |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
| Science and Technology Commission of Shanghai Municipality | 16DZ2260200 |
| Science and Technology Commission of Shanghai Municipality | |
| Ministry of Science and Technology, Taiwan | 105-2112-M-002-017-MY3 |
| Ministry of Science and Technology, Taiwan | |
| National Science Foundation | PHY 1653405 |
| National Science Foundation |
Keywords
- Global QCD fits
- Lattice QCD
- Unpolarized/polarized parton distribution functions (PDFs)