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Title: Nucleon structure with two flavors of dynamical domain-wall fermions

Abstract

We present a numerical lattice quantum chromodynamics calculation of isovector form factors and the first few moments of the isovector structure functions of the nucleon. The calculation employs two degenerate dynamical flavors of domain-wall fermions, resulting in good control of chiral symmetry breaking. Nonperturbative renormalization of the relevant quark currents is performed where necessary. The DBW2 gauge action is used to further improve the chiral behavior while maintaining a reasonable physical lattice volume. The inverse lattice spacing, a{sup -1}, is approximately 1.7 GeV. Degenerate up and down dynamical quark masses of approximately 1, 3/4 and 1/2 times the strange quark mass are used. The physical volume of the lattice is about (1.9 fm){sup 3}. The ratio of the isovector vector to axial charges, g{sub A}/g{sub V}, tends to a lower value than the experimental value as the quark mass is reduced toward the physical point. Momentum-transfer dependences of the isovector vector, axial, induced-tensor and induced-pseudoscalar form factors are calculated. The Goldberger-Treiman relation holds at low momentum transfer and yields an estimation of the pion-nucleon coupling, g{sub {pi}}{sub NN}=15.5(1.4), where the quoted error is only statistical. We find that the flavor nonsinglet quark momentum fraction <x>{sub u-d} and quark helicity fractionmore » <x>{sub {delta}}{sub u-{delta}}{sub d} overshoot their experimental values after linear chiral extrapolation. We discuss possible systematic errors for this discrepancy. An estimate for transversity, <1>{sub {delta}}{sub u-{delta}}{sub d}=0.93(6) in MS at 2 GeV, is obtained and a twist-3 polarized moment, d{sub 1}, appears small, suggesting that the Wandzura-Wilczek relation holds approximately. We discuss in detail the systematic errors in the calculation, with particular attention paid to finite volume, excited-state contamination, and chiral extrapolations.« less

Authors:
 [1]; ;  [2];  [2];  [3]
  1. Jefferson Laboratory, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)
  2. RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  3. Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113 (Japan)
Publication Date:
OSTI Identifier:
21250244
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 78; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevD.78.014505; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHIRAL SYMMETRY; CHIRALITY; COMPUTERIZED SIMULATION; EXCITED STATES; EXTRAPOLATION; FLAVOR MODEL; FORM FACTORS; GEV RANGE 01-10; GOLDBERGER-TREIMAN RELATION; HELICITY; ISOVECTORS; LATTICE FIELD THEORY; MASS; MOMENTUM TRANSFER; NUCLEONS; PION-NUCLEON INTERACTIONS; QUANTUM CHROMODYNAMICS; RENORMALIZATION; S QUARKS; STRUCTURE FUNCTIONS; SYMMETRY BREAKING

Citation Formats

Lin, H -W, RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, Blum, Tom, Yamazaki, Takeshi, Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, Ohta, Shigemi, Institute of Particle and Nuclear Studies, KEK, Tsukuba, 305-0801, Physics Department, Sokendai Graduate U. Adv. Studies, Hayama, Kanagawa 240-0193, and Sasaki, Shoichi. Nucleon structure with two flavors of dynamical domain-wall fermions. United States: N. p., 2008. Web. doi:10.1103/PHYSREVD.78.014505.
Lin, H -W, RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, Blum, Tom, Yamazaki, Takeshi, Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, Ohta, Shigemi, Institute of Particle and Nuclear Studies, KEK, Tsukuba, 305-0801, Physics Department, Sokendai Graduate U. Adv. Studies, Hayama, Kanagawa 240-0193, & Sasaki, Shoichi. Nucleon structure with two flavors of dynamical domain-wall fermions. United States. doi:10.1103/PHYSREVD.78.014505.
Lin, H -W, RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, Blum, Tom, Yamazaki, Takeshi, Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, Ohta, Shigemi, Institute of Particle and Nuclear Studies, KEK, Tsukuba, 305-0801, Physics Department, Sokendai Graduate U. Adv. Studies, Hayama, Kanagawa 240-0193, and Sasaki, Shoichi. Tue . "Nucleon structure with two flavors of dynamical domain-wall fermions". United States. doi:10.1103/PHYSREVD.78.014505.
@article{osti_21250244,
title = {Nucleon structure with two flavors of dynamical domain-wall fermions},
author = {Lin, H -W and RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 and Blum, Tom and Yamazaki, Takeshi and Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046 and Ohta, Shigemi and Institute of Particle and Nuclear Studies, KEK, Tsukuba, 305-0801 and Physics Department, Sokendai Graduate U. Adv. Studies, Hayama, Kanagawa 240-0193 and Sasaki, Shoichi},
abstractNote = {We present a numerical lattice quantum chromodynamics calculation of isovector form factors and the first few moments of the isovector structure functions of the nucleon. The calculation employs two degenerate dynamical flavors of domain-wall fermions, resulting in good control of chiral symmetry breaking. Nonperturbative renormalization of the relevant quark currents is performed where necessary. The DBW2 gauge action is used to further improve the chiral behavior while maintaining a reasonable physical lattice volume. The inverse lattice spacing, a{sup -1}, is approximately 1.7 GeV. Degenerate up and down dynamical quark masses of approximately 1, 3/4 and 1/2 times the strange quark mass are used. The physical volume of the lattice is about (1.9 fm){sup 3}. The ratio of the isovector vector to axial charges, g{sub A}/g{sub V}, tends to a lower value than the experimental value as the quark mass is reduced toward the physical point. Momentum-transfer dependences of the isovector vector, axial, induced-tensor and induced-pseudoscalar form factors are calculated. The Goldberger-Treiman relation holds at low momentum transfer and yields an estimation of the pion-nucleon coupling, g{sub {pi}}{sub NN}=15.5(1.4), where the quoted error is only statistical. We find that the flavor nonsinglet quark momentum fraction <x>{sub u-d} and quark helicity fraction <x>{sub {delta}}{sub u-{delta}}{sub d} overshoot their experimental values after linear chiral extrapolation. We discuss possible systematic errors for this discrepancy. An estimate for transversity, <1>{sub {delta}}{sub u-{delta}}{sub d}=0.93(6) in MS at 2 GeV, is obtained and a twist-3 polarized moment, d{sub 1}, appears small, suggesting that the Wandzura-Wilczek relation holds approximately. We discuss in detail the systematic errors in the calculation, with particular attention paid to finite volume, excited-state contamination, and chiral extrapolations.},
doi = {10.1103/PHYSREVD.78.014505},
journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 1,
volume = 78,
place = {United States},
year = {2008},
month = {7}
}