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Title: Threshold pion photoproduction of nucleons in the chiral quark model

Abstract

In this paper, we show that the low energy theorem (LET) of threshold pion photoproduction can be fully recovered in the quark model. An essential result of this investigation is that the quark-pion operators are obtained from the effective chiral Lagrangian, and the low energy theorem does not require constraints on the internal structures of the nucleon. Changing from pseudovector to pseudoscalar quark-pion couplings generates an additional term at order [mu]=[ital m][sub [pi]]/[ital M] only in the isospin amplitude [ital A][sup ([minus])]. The role of the transitions between the nucleon and the resonance [ital P][sub 33](1232) or [ital P]-wave baryons is also discussed; we find that the leading contributions to the isospin amplitudes at [ital O]([mu][sup 2]) are from the transition between the [ital P]-wave baryons and the nucleon, and from the charge radius of the nucleon. The leading contribution from the [ital P]-wave baryons only affects neutral pion production, and improves the agreement with data significantly. The transition between the resonance [ital P][sub 33](1232) and the nucleon only gives an order [mu][sup 3] correction to [ital A][sup ([minus])].

Authors:
 [1]
  1. Physics Department, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213-3890 (United States)
Publication Date:
OSTI Identifier:
6962639
Resource Type:
Journal Article
Journal Name:
Physical Review, D (Particles Fields); (United States)
Additional Journal Information:
Journal Volume: 50:9; Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; NUCLEONS; PHOTOPRODUCTION; QUARK MODEL; BARYONS; CHIRAL SYMMETRY; COUPLING; LAGRANGIAN FUNCTION; LOW-ENERGY THEOREM; P WAVES; PIONS; BASIC INTERACTIONS; BOSONS; COMPOSITE MODELS; ELECTROMAGNETIC INTERACTIONS; ELEMENTARY PARTICLES; FERMIONS; FUNCTIONS; HADRONS; INTERACTIONS; MATHEMATICAL MODELS; MESONS; PARTIAL WAVES; PARTICLE INTERACTIONS; PARTICLE MODELS; PARTICLE PRODUCTION; PSEUDOSCALAR MESONS; SYMMETRY; 662340* - Hadron Interactions- (1992-); 662240 - Models for Strong Interactions- (1992-); 662390 - Electromagnetic Processes & Properties- (1992-); 662330 - Photon & Charged-Lepton Interactions with Hadrons- (1992)

Citation Formats

Li, Z. Threshold pion photoproduction of nucleons in the chiral quark model. United States: N. p., 1994. Web. doi:10.1103/PhysRevD.50.5639.
Li, Z. Threshold pion photoproduction of nucleons in the chiral quark model. United States. https://doi.org/10.1103/PhysRevD.50.5639
Li, Z. 1994. "Threshold pion photoproduction of nucleons in the chiral quark model". United States. https://doi.org/10.1103/PhysRevD.50.5639.
@article{osti_6962639,
title = {Threshold pion photoproduction of nucleons in the chiral quark model},
author = {Li, Z},
abstractNote = {In this paper, we show that the low energy theorem (LET) of threshold pion photoproduction can be fully recovered in the quark model. An essential result of this investigation is that the quark-pion operators are obtained from the effective chiral Lagrangian, and the low energy theorem does not require constraints on the internal structures of the nucleon. Changing from pseudovector to pseudoscalar quark-pion couplings generates an additional term at order [mu]=[ital m][sub [pi]]/[ital M] only in the isospin amplitude [ital A][sup ([minus])]. The role of the transitions between the nucleon and the resonance [ital P][sub 33](1232) or [ital P]-wave baryons is also discussed; we find that the leading contributions to the isospin amplitudes at [ital O]([mu][sup 2]) are from the transition between the [ital P]-wave baryons and the nucleon, and from the charge radius of the nucleon. The leading contribution from the [ital P]-wave baryons only affects neutral pion production, and improves the agreement with data significantly. The transition between the resonance [ital P][sub 33](1232) and the nucleon only gives an order [mu][sup 3] correction to [ital A][sup ([minus])].},
doi = {10.1103/PhysRevD.50.5639},
url = {https://www.osti.gov/biblio/6962639}, journal = {Physical Review, D (Particles Fields); (United States)},
issn = {0556-2821},
number = ,
volume = 50:9,
place = {United States},
year = {1994},
month = {11}
}