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Title: Chiral Effective-Field Theory in the $$\Delta$$(1232) Region: I. Pion Electroproduction on the Nucleon

Abstract

We develop an extension of chiral perturbation theory to the {Delta}(1232)-resonance energy region and apply it to investigate the pion electroproduction off the nucleon (e{sup -} N {yields} e{sup -} N {pi}). We present a complete calculation of this process, in the {Delta}-resonance region, up to next-to-leading order in the {delta}-expansion. At this order, the only free parameters are the three low-energy constants corresponding to the magnetic (M1), electric (E2), and Coulomb (C2) {gamma} N {yields} {Delta} transition strength. After fitting these parameters to a few well-known data, our calculation provides a prediction for observables and multipole amplitudes of pion electroproduction. These results compare favorably with the phenomenological multipole solutions and recent experimental results from MIT-Bates and MAMI. Our prediction for the pion-mass dependence of the {gamma}N{Delta} form factors offers an explanation for the discrepancy between the recent lattice-QCD results and the experimental value for the ''C2/M1 ratio'' at low Q{sup 2}.

Authors:
;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
862406
Report Number(s):
JLAB-THY-06-458; DOE/ER/40150-3672
TRN: US0600696
DOE Contract Number:  
AC05-84ER40150
Resource Type:
Journal Article
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AMPLITUDES; ELECTROPRODUCTION; FORECASTING; FORM FACTORS; MULTIPOLES; NUCLEONS; PERTURBATION THEORY; PIONS

Citation Formats

Pascalutsa, Vladimir, and Vanderhaeghen, Marc. Chiral Effective-Field Theory in the $\Delta$(1232) Region: I. Pion Electroproduction on the Nucleon. United States: N. p., 2006. Web.
Pascalutsa, Vladimir, & Vanderhaeghen, Marc. Chiral Effective-Field Theory in the $\Delta$(1232) Region: I. Pion Electroproduction on the Nucleon. United States.
Pascalutsa, Vladimir, and Vanderhaeghen, Marc. Fri . "Chiral Effective-Field Theory in the $\Delta$(1232) Region: I. Pion Electroproduction on the Nucleon". United States. https://www.osti.gov/servlets/purl/862406.
@article{osti_862406,
title = {Chiral Effective-Field Theory in the $\Delta$(1232) Region: I. Pion Electroproduction on the Nucleon},
author = {Pascalutsa, Vladimir and Vanderhaeghen, Marc},
abstractNote = {We develop an extension of chiral perturbation theory to the {Delta}(1232)-resonance energy region and apply it to investigate the pion electroproduction off the nucleon (e{sup -} N {yields} e{sup -} N {pi}). We present a complete calculation of this process, in the {Delta}-resonance region, up to next-to-leading order in the {delta}-expansion. At this order, the only free parameters are the three low-energy constants corresponding to the magnetic (M1), electric (E2), and Coulomb (C2) {gamma} N {yields} {Delta} transition strength. After fitting these parameters to a few well-known data, our calculation provides a prediction for observables and multipole amplitudes of pion electroproduction. These results compare favorably with the phenomenological multipole solutions and recent experimental results from MIT-Bates and MAMI. Our prediction for the pion-mass dependence of the {gamma}N{Delta} form factors offers an explanation for the discrepancy between the recent lattice-QCD results and the experimental value for the ''C2/M1 ratio'' at low Q{sup 2}.},
doi = {},
url = {https://www.osti.gov/biblio/862406}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2006},
month = {1}
}