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Title: Insights into nucleon structure from parton distributions

Abstract

We review recent progress in understanding the substructure of the nucleon from global QCD analysis of parton distribution functions (PDFs). New high-precision data onW-boson production in p ¯ p collisions have significantly reduced the uncertainty on the d=u PDF ratio at large values of x, indirectly constraining models of the medium modification of bound nucleons. Drell-Yan data from pp and pd scattering reveal new information on the d¯-u¯ asymmetry, clarifying the role of chiral symmetry breaking in the nucleon. In the strange sector, a new chiral SU(3) analysis finds a valence-like component of the strange-quark PDF, giving rise to a nontrivial s- ¯ s asymmetry at moderate x values. We also review recent analyses of charm in the nucleon, which have found conflicting indications of the size of the nonperturbative charm component.

Authors:
 [1]
  1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1360724
Report Number(s):
JLAB-THY-17-2466; DOE/OR/23177-4150
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Journal Name: Proceedings of Science; Journal Volume: INPC2016; Conference: INPC2016, Adelaide, Australia, September 11-16, 2016
Country of Publication:
United States
Language:
English

Citation Formats

Melnitchouk, Wally. Insights into nucleon structure from parton distributions. United States: N. p., 2017. Web.
Melnitchouk, Wally. Insights into nucleon structure from parton distributions. United States.
Melnitchouk, Wally. Mon . "Insights into nucleon structure from parton distributions". United States. doi:. https://www.osti.gov/servlets/purl/1360724.
@article{osti_1360724,
title = {Insights into nucleon structure from parton distributions},
author = {Melnitchouk, Wally},
abstractNote = {We review recent progress in understanding the substructure of the nucleon from global QCD analysis of parton distribution functions (PDFs). New high-precision data onW-boson production in p ¯ p collisions have significantly reduced the uncertainty on the d=u PDF ratio at large values of x, indirectly constraining models of the medium modification of bound nucleons. Drell-Yan data from pp and pd scattering reveal new information on the d¯-u¯ asymmetry, clarifying the role of chiral symmetry breaking in the nucleon. In the strange sector, a new chiral SU(3) analysis finds a valence-like component of the strange-quark PDF, giving rise to a nontrivial s- ¯ s asymmetry at moderate x values. We also review recent analyses of charm in the nucleon, which have found conflicting indications of the size of the nonperturbative charm component.},
doi = {},
journal = {Proceedings of Science},
number = ,
volume = INPC2016,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Conference:
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  • This talk presents recent calculations in full QCD of the lowest three moments of generalized parton distributions and the insight they provide into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon. In addition, new exploratory calculations in the chiral regime of full QCD are discussed.
  • The lowest three moments of generalized parton distributions are calculated in full QCD and provide new insight into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon.
  • The current experimental status of measurements of nucleon structure functions in deep inelastic lepton scattering is presented. Recent BCDMS and SLAC results provide a consistent data set for charged lepton scattering. New probes of parton distributions: direct photons, Drell Yan di-muon production, W, Z and heavy quark production are providing information on the gluon an antiquark distributions. The implications of these data on our understanding of the structure of the nucleon, and the structure of the nucleon in the nucleus are discussed. 26 refs., 9 figs.
  • This paper discusses a selected part of the experimental program dedicated to the study of Generalized Parton Distributions, a recently introduced concept which provides a comprehensive framework for investigations of the partonic structure of the nucleon. Particular emphasis is put on the Deeply Virtual Compton Scattering program performed at the Jefferson Laboratory. The short and long term future of this program is also discussed in the context of the several experimental efforts aiming at a complete and exhaustive mapping of Generalized Parton Distributions.
  • Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297MeV, on a lattice with spacing 0.084fm, selected TMD observables are accessed and compared to previous explorations at heavier pion masses on coarser lattices.