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This content will become publicly available on February 11, 2015

Title: Quasi-parton distribution functions: A study in the diquark spectator model

A set of quasi-parton distribution functions (quasi-PDFs) have been recently proposed by Ji. Defined as the matrix elements of equal-time spatial correlations, they can be computed on the lattice and should reduce to the standard PDFs when the proton momentum Pz is very large. Since taking the Pz → ∞ limit is not feasible in lattice simulations, it is essential to provide guidance for which values of Pz the quasi-PDFs are good approximations of standard PDFs. Within the framework of the spectator diquark model, we evaluate both the up and down quarks' quasi-PDFs and standard PDFs for all leading-twist distributions (unpolarized distribution f₁, helicity distribution g₁, and transversity distribution h₁). We find that, for intermediate parton momentum fractions x , quasi-PDFs are good approximations to standard PDFs (within 20–30%) when Pz ≳ 1.5–2 GeV. On the other hand, for large x~1 much larger Pz > 4 GeV is necessary to obtain a satisfactory agreement between the two sets. We further test the Soffer positivity bound, and find that it does not hold in general for quasi-PDFs.
Authors:
 [1] ;  [2] ;  [2] ;  [2]
  1. Penn State Berks, Reading, PA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
OSTI Identifier:
1198586
Grant/Contract Number:
FG02-07ER41460; AC02-05CH11231; 20130783PRD2; 20130019DR
Type:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 743; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS