Light-front representation of chiral dynamics in peripheral transverse densities

Open Access
Regular Article - Theoretical Physics

Abstract

The nucleon’s electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances b = O(Mπ− 1) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independent and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.

Keywords

Electromagnetic Processes and Properties Chiral Lagrangians Parton Model 

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Copyright information

© The Author(s) 2015

Authors and Affiliations

  1. 1.Department of Physics and AstronomyUppsala UniversityUppsalaSweden
  2. 2.Theory Center, Jefferson LabNewport NewsU.S.A.

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