skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Extraction and interpretation of {gamma}N{yields}{delta} form factors within a dynamical model

Abstract

Within the dynamical model of Refs. [Phys. Rev. C 54, 2660 (1996); 63, 055201 (2001)], we perform an analysis of recent data of pion electroproduction reactions at energies near the {delta}(1232) resonance. We discuss possible interpretations of the extracted bare and dressed {gamma}N{yields}{delta} form factors in terms of relativistic constituent quark models and lattice quantum chromodynamics calculations. Possible future developments are discussed.

Authors:
 [1];  [2];  [1];  [3];  [1];  [4];  [5];  [3]
  1. Excited Baryon Analysis Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 22901 (United States)
  2. (Spain)
  3. (United States)
  4. (Japan)
  5. Excited Baryon Analysis Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 22901, USA (United States)
Publication Date:
OSTI Identifier:
20990973
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.75.015205; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; DELTA-1232 BARYONS; ELECTROPRODUCTION; EXTRACTION; FORM FACTORS; PIONS; QUANTUM CHROMODYNAMICS; QUARK MODEL; RELATIVISTIC RANGE

Citation Formats

Julia-Diaz, B., Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, E-08028 Barcelona, Lee, T.-S. H., Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, Sato, T., Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Smith, L. C., and Physics Department, University of Virginia, Charlottesville, Virginia 22901. Extraction and interpretation of {gamma}N{yields}{delta} form factors within a dynamical model. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.015205.
Julia-Diaz, B., Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, E-08028 Barcelona, Lee, T.-S. H., Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, Sato, T., Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Smith, L. C., & Physics Department, University of Virginia, Charlottesville, Virginia 22901. Extraction and interpretation of {gamma}N{yields}{delta} form factors within a dynamical model. United States. doi:10.1103/PHYSREVC.75.015205.
Julia-Diaz, B., Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, E-08028 Barcelona, Lee, T.-S. H., Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, Sato, T., Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Smith, L. C., and Physics Department, University of Virginia, Charlottesville, Virginia 22901. Mon . "Extraction and interpretation of {gamma}N{yields}{delta} form factors within a dynamical model". United States. doi:10.1103/PHYSREVC.75.015205.
@article{osti_20990973,
title = {Extraction and interpretation of {gamma}N{yields}{delta} form factors within a dynamical model},
author = {Julia-Diaz, B. and Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, E-08028 Barcelona and Lee, T.-S. H. and Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 and Sato, T. and Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 and Smith, L. C. and Physics Department, University of Virginia, Charlottesville, Virginia 22901},
abstractNote = {Within the dynamical model of Refs. [Phys. Rev. C 54, 2660 (1996); 63, 055201 (2001)], we perform an analysis of recent data of pion electroproduction reactions at energies near the {delta}(1232) resonance. We discuss possible interpretations of the extracted bare and dressed {gamma}N{yields}{delta} form factors in terms of relativistic constituent quark models and lattice quantum chromodynamics calculations. Possible future developments are discussed.},
doi = {10.1103/PHYSREVC.75.015205},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 75,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • Within the dynamical model of Refs. [Phys. Rev. C54, 2660 (1996); C63, 055201 (2001)], we perform an analysis of recent data of pion electroproduction reactions at energies near the {Delta}(1232) resonance. We discuss possible interpretations of the extracted bare and dressed {gamma} N {yields} {Delta} form factors in terms of relativistic constituent quark models and Lattice QCD calculations. Possible future developments are discussed.
  • We obtain the electromagnetic form factors of the {gamma}N{Delta} transition by analyzing recent pion-electroproduction data using a fully relativistic dynamical model. Special care is taken to satisfy Ward-Takahashi identities for the Born term in the presence of form factors thereby allowing the use of realistic electromagnetic form factors of the nucleon and pion. We parameterize the Q{sup 2} dependence of the bare {gamma}N{Delta} form factors by a three-parameter form which is consistent with the asymptotic behavior inferred from QCD. The parameters of the bare {gamma}N{Delta} form factors are the only free parameters of the model and are fitted to themore » differential cross-section and multipole-analysis data up to Q{sup 2} = 4 (GeV/c){sup 2} in the {Delta}(1232)-resonance region. This analysis emphasizes the significance of the pion-cloud effects in the extraction of the resonance parameters.« less
  • We obtain the electromagnetic form factors of the {gamma}N{delta} transition by analyzing recent pion-electroproduction data using a fully relativistic dynamical model. Special care is taken to satisfy Ward-Takahashi identities for the Born term in the presence of form factors, thereby allowing the use of realistic electromagnetic form factors of the nucleon and pion. We parametrize the Q{sup 2} dependence of the bare {gamma}N{delta} form factors by a three-parameter form which is consistent with the asymptotic behavior inferred from QCD. The parameters of the bare {gamma}N{delta} form factors are the only free parameters of the model and are fitted to themore » differential cross-section and multipole-analysis data up to Q{sup 2}=4(GeV/c){sup 2} in the {delta}(1232)-resonance region. This analysis emphasizes the significance of the pion-cloud effects in the extraction of the resonance parameters.« less
  • We explain the application of a recently developed analytic continuation method to extract the electromagnetic transition form factors for the nucleon resonances (more » $N^*$) within a dynamical coupled-channel model of meson-baryon reactions.Illustrative results of the obtained $$N^*\rightarrow \gamma N$$ transition form factors, defined at the resonance pole positions on the complex energy plane, for the well isolated $$P_{33}$$ and $$D_{13}$$, and the complicated $$P_{11}$$ resonances are presented. A formula has been developed to give an unified representation of the effects due to the first two $$P_{11}$$ poles, which are near the $$\pi\Delta$$ threshold, but are on different Riemann sheets. We also find that a simple formula, with its parameters determined in the Laurent expansions of $$\pi N \rightarrow \pi N$$ and $$\gamma N \rightarrow\pi N$$ amplitudes, can reproduce to a very large extent the exact solutions of the considered model at energies near the real parts of the extracted resonance positions. We indicate the differences between our results and those extracted from the approaches using the Breit-Wigner parametrization of resonant amplitudes to fit the data.« less
  • No abstract prepared.