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Title: Nucleon form factors from quenched lattice QCD with domain wall fermions

Abstract

We present a quenched lattice calculation of the weak nucleon form factors: vector [F{sub V}(q{sup 2})], induced tensor [F{sub T}(q{sup 2})], axial vector [F{sub A}(q{sup 2})] and induced pseudoscalar [F{sub P}(q{sup 2})] form factors. Our simulations are performed on three different lattice sizes L{sup 3}xT=24{sup 3}x32, 16{sup 3}x32, and 12{sup 3}x32 with a lattice cutoff of a{sup -1}{approx_equal}1.3 GeV and light quark masses down to about 1/4 the strange quark mass (m{sub {pi}}{approx_equal}390 MeV) using a combination of the DBW2 gauge action and domain wall fermions. The physical volume of our largest lattice is about (3.6 fm){sup 3}, where the finite volume effects on form factors become negligible and the lower momentum transfers (q{sup 2}{approx_equal}0.1 GeV{sup 2}) are accessible. The q{sup 2} dependences of form factors in the low q{sup 2} region are examined. It is found that the vector, induced tensor, and axial-vector form factors are well described by the dipole form, while the induced pseudoscalar form factor is consistent with pion-pole dominance. We obtain the ratio of axial to vector coupling g{sub A}/g{sub V}=F{sub A}(0)/F{sub V}(0)=1.219(38) and the pseudoscalar coupling g{sub P}=m{sub {mu}}F{sub P}(0.88m{sub {mu}}{sup 2})=8.15(54), where the errors are statistical errors only. These values agree with experimentalmore » values from neutron {beta} decay and muon capture on the proton. However, the root mean-squared radii of the vector, induced tensor, and axial vector underestimate the known experimental values by about 20%. We also calculate the pseudoscalar nucleon matrix element in order to verify the axial Ward-Takahashi identity in terms of the nucleon matrix elements, which may be called as the generalized Goldberger-Treiman relation.« less

Authors:
 [1];  [2]
  1. Department of Physics, University of Tokyo, Hongo 7-3-1, Tokyo 113-0033 (Japan)
  2. Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046 (United States)
Publication Date:
OSTI Identifier:
21250249
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.78.014510; (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; BETA DECAY; CAPTURE; COUPLING; D QUARKS; DIPOLES; FORM FACTORS; GEV RANGE 01-10; GOLDBERGER-TREIMAN RELATION; LATTICE FIELD THEORY; MASS; MATRIX ELEMENTS; MEV RANGE 100-1000; MOMENTUM TRANSFER; MUONS; NEUTRONS; PIONS; PROTONS; QUANTUM CHROMODYNAMICS; S QUARKS; SIMULATION; U QUARKS

Citation Formats

Sasaki, Shoichi, and Yamazaki, Takeshi. Nucleon form factors from quenched lattice QCD with domain wall fermions. United States: N. p., 2008. Web. doi:10.1103/PHYSREVD.78.014510.
Sasaki, Shoichi, & Yamazaki, Takeshi. Nucleon form factors from quenched lattice QCD with domain wall fermions. United States. https://doi.org/10.1103/PHYSREVD.78.014510
Sasaki, Shoichi, and Yamazaki, Takeshi. Tue . "Nucleon form factors from quenched lattice QCD with domain wall fermions". United States. https://doi.org/10.1103/PHYSREVD.78.014510.
@article{osti_21250249,
title = {Nucleon form factors from quenched lattice QCD with domain wall fermions},
author = {Sasaki, Shoichi and Yamazaki, Takeshi},
abstractNote = {We present a quenched lattice calculation of the weak nucleon form factors: vector [F{sub V}(q{sup 2})], induced tensor [F{sub T}(q{sup 2})], axial vector [F{sub A}(q{sup 2})] and induced pseudoscalar [F{sub P}(q{sup 2})] form factors. Our simulations are performed on three different lattice sizes L{sup 3}xT=24{sup 3}x32, 16{sup 3}x32, and 12{sup 3}x32 with a lattice cutoff of a{sup -1}{approx_equal}1.3 GeV and light quark masses down to about 1/4 the strange quark mass (m{sub {pi}}{approx_equal}390 MeV) using a combination of the DBW2 gauge action and domain wall fermions. The physical volume of our largest lattice is about (3.6 fm){sup 3}, where the finite volume effects on form factors become negligible and the lower momentum transfers (q{sup 2}{approx_equal}0.1 GeV{sup 2}) are accessible. The q{sup 2} dependences of form factors in the low q{sup 2} region are examined. It is found that the vector, induced tensor, and axial-vector form factors are well described by the dipole form, while the induced pseudoscalar form factor is consistent with pion-pole dominance. We obtain the ratio of axial to vector coupling g{sub A}/g{sub V}=F{sub A}(0)/F{sub V}(0)=1.219(38) and the pseudoscalar coupling g{sub P}=m{sub {mu}}F{sub P}(0.88m{sub {mu}}{sup 2})=8.15(54), where the errors are statistical errors only. These values agree with experimental values from neutron {beta} decay and muon capture on the proton. However, the root mean-squared radii of the vector, induced tensor, and axial vector underestimate the known experimental values by about 20%. We also calculate the pseudoscalar nucleon matrix element in order to verify the axial Ward-Takahashi identity in terms of the nucleon matrix elements, which may be called as the generalized Goldberger-Treiman relation.},
doi = {10.1103/PHYSREVD.78.014510},
url = {https://www.osti.gov/biblio/21250249}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 1,
volume = 78,
place = {United States},
year = {2008},
month = {7}
}