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Title: Up, down, and strange nucleon axial form factors from lattice QCD

Abstract

Here, we report a calculation of the nucleon axial form factors $$G_A^q(Q^2)$$ and $$G_P^q(Q^2)$$ for all three light quark flavors $$q\in\{u,d,s\}$$ in the range $$0\leq Q^2\lesssim 1.2\text{ GeV}^2$$ using lattice QCD. Our work was done using a single ensemble with pion mass 317 MeV and made use of the hierarchical probing technique to efficiently evaluate the required disconnected loops. We perform nonperturbative renormalization of the axial current, including a nonperturbative treatment of the mixing between light and strange currents due to the singlet-nonsinglet difference caused by the axial anomaly. The form factor shapes are fit using the model-independent $z$ expansion. From $$G_A^q(Q^2)$$, we determine the quark contributions to the nucleon spin and axial radii. By extrapolating the isovector $$G_P^{u-d}(Q^2)$$, we obtain the induced pseudoscalar coupling relevant for ordinary muon capture and the pion-nucleon coupling constant. We also found that the disconnected contributions to $$G_P$$ form factors are large, and give an interpretation based on the dominant influence of the pseudoscalar poles in these form factors.

Authors:
 [1];  [2];  [3];  [4];  [2];  [5];  [6];  [7];  [6];  [8]
  1. John von Neumann-Institute for Computing (NIC), Zeuthen (Germany)
  2. Bergische Univ., Wuppertal (Germany); Julich Research Centre (Germany). Inst. for Advanced Simulation (IAS)
  3. Univ. of Arizona, Tucson, AZ (United States). Dept. of Physics; Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center
  4. New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics
  5. College of William and Mary, Williamsburg, VA (United States). Dpet. of Computer Science
  6. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Center for Theoretical Physics
  7. College of William and Mary, Williamsburg, VA (United States). Physics Dept. ; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  8. 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), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1364529
Alternate Identifier(s):
OSTI ID: 1363979
Report Number(s):
JLAB-THY-17-2498; DOE/OR/23177-4172; arXiv:1703.06703; RBRC 1232
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:
FG02-94ER40818; SC-0011090; FG02-96ER40965; FC02-12ER41890; FG02-04ER41302; AC02-05HC11231; AC05-06OR23177; ACI-1053575; CCF-121834; PHY-1520996; SFB-TRR 55; FG02–94ER40818; SC–0011090; FG02–96ER40965; FC02–12ER41890; FG02–04ER41302; AC02–05HC11231; AC05–06OR23177
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 95; Journal Issue: 11; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Green, Jeremy, Hasan, Nesreen, Meinel, Stefan, Engelhardt, Michael, Krieg, Stefan, Laeuchli, Jesse, Negele, John, Orginos, Kostas, Pochinsky, Andrew, and Syritsyn, Sergey. Up, down, and strange nucleon axial form factors from lattice QCD. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.95.114502.
Green, Jeremy, Hasan, Nesreen, Meinel, Stefan, Engelhardt, Michael, Krieg, Stefan, Laeuchli, Jesse, Negele, John, Orginos, Kostas, Pochinsky, Andrew, & Syritsyn, Sergey. Up, down, and strange nucleon axial form factors from lattice QCD. United States. doi:10.1103/PhysRevD.95.114502.
Green, Jeremy, Hasan, Nesreen, Meinel, Stefan, Engelhardt, Michael, Krieg, Stefan, Laeuchli, Jesse, Negele, John, Orginos, Kostas, Pochinsky, Andrew, and Syritsyn, Sergey. Wed . "Up, down, and strange nucleon axial form factors from lattice QCD". United States. doi:10.1103/PhysRevD.95.114502.
@article{osti_1364529,
title = {Up, down, and strange nucleon axial form factors from lattice QCD},
author = {Green, Jeremy and Hasan, Nesreen and Meinel, Stefan and Engelhardt, Michael and Krieg, Stefan and Laeuchli, Jesse and Negele, John and Orginos, Kostas and Pochinsky, Andrew and Syritsyn, Sergey},
abstractNote = {Here, we report a calculation of the nucleon axial form factors $G_A^q(Q^2)$ and $G_P^q(Q^2)$ for all three light quark flavors $q\in\{u,d,s\}$ in the range $0\leq Q^2\lesssim 1.2\text{ GeV}^2$ using lattice QCD. Our work was done using a single ensemble with pion mass 317 MeV and made use of the hierarchical probing technique to efficiently evaluate the required disconnected loops. We perform nonperturbative renormalization of the axial current, including a nonperturbative treatment of the mixing between light and strange currents due to the singlet-nonsinglet difference caused by the axial anomaly. The form factor shapes are fit using the model-independent $z$ expansion. From $G_A^q(Q^2)$, we determine the quark contributions to the nucleon spin and axial radii. By extrapolating the isovector $G_P^{u-d}(Q^2)$, we obtain the induced pseudoscalar coupling relevant for ordinary muon capture and the pion-nucleon coupling constant. We also found that the disconnected contributions to $G_P$ form factors are large, and give an interpretation based on the dominant influence of the pseudoscalar poles in these form factors.},
doi = {10.1103/PhysRevD.95.114502},
journal = {Physical Review D},
number = 11,
volume = 95,
place = {United States},
year = {Wed Jun 14 00:00:00 EDT 2017},
month = {Wed Jun 14 00:00:00 EDT 2017}
}

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Cited by: 10works
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  • Cited by 10
  • We evaluate the nucleon axial form factor, G{sub A}(q{sup 2}), and induced pseudoscalar form factor, G{sub p}(q{sup 2}), as well as the pion-nucleon form factor, G{sub {pi}}{sub NN}(q{sup 2}), in lattice QCD. We also evaluate the corresponding nucleon to {delta} transition form factors, C{sub 5}{sup A}(q{sup 2}) and C{sub 6}{sup A}(q{sup 2}), and the pion-nucleon-{delta} form factor G{sub {pi}}{sub N{delta}}(q{sup 2}). The nucleon form factors are evaluated in the quenched theory and with two degenerate flavors of dynamical Wilson fermions. The nucleon to {delta} form factors, besides Wilson fermions, are evaluated using domain wall valence fermions with staggered sea quarkmore » configurations for pion masses as low as about 350 MeV. Using these form factors, together with an evaluation of the renormalized quark mass, we investigate the validity of the diagonal and nondiagonal Goldberger-Treiman relations. The ratios G{sub {pi}}{sub N{delta}}(q{sup 2})/G{sub {pi}}{sub NN}(q{sup 2}) and 2C{sub 5}{sup A}(q{sup 2})/G{sub A}(q{sup 2}) are constant as a function of the momentum transfer squared and show almost no dependence on the quark mass. We confirm equality of these two ratios consistent with the Goldberger-Treiman relations extracting a mean value of 1.61(2)« less
  • No abstract prepared.
  • We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cut-off effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.
  • Cited by 2