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Title: Chiral dynamics and peripheral transverse densities

Abstract

In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral componentsmore » of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.« less

Authors:
 [1];  [2]
  1. Uppsala University (Sweden)
  2. JLAB, 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)
OSTI Identifier:
1117511
Report Number(s):
JLAB-THY-13-1763; DOE/OR-23177-2641
Journal ID: ISSN 1029-8479; TRN: US1400167
DOE Contract Number:  
AC05-06OR23177
Resource Type:
Journal Article
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Volume: 1401; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Elastic form factors, dispersion relations, chiral effective field theory, 1/Nc expansion, transverse charge and magnetization densities, generalized parton distributions, light–front quantization

Citation Formats

Granados, Carlos G., and Weiss, Christian. Chiral dynamics and peripheral transverse densities. United States: N. p., 2014. Web. doi:10.1007/JHEP01(2014)092.
Granados, Carlos G., & Weiss, Christian. Chiral dynamics and peripheral transverse densities. United States. doi:10.1007/JHEP01(2014)092.
Granados, Carlos G., and Weiss, Christian. Wed . "Chiral dynamics and peripheral transverse densities". United States. doi:10.1007/JHEP01(2014)092. https://www.osti.gov/servlets/purl/1117511.
@article{osti_1117511,
title = {Chiral dynamics and peripheral transverse densities},
author = {Granados, Carlos G. and Weiss, Christian},
abstractNote = {In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral components of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.},
doi = {10.1007/JHEP01(2014)092},
journal = {Journal of High Energy Physics (Online)},
issn = {1029-8479},
number = ,
volume = 1401,
place = {United States},
year = {2014},
month = {1}
}