Ward-Takahashi identities for the radiative axial-vector vertex and low-energy theorem for the pion electroproduction

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.46.2519· OSTI ID:7199240

Ohta, K ^[1]

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1. Institute of Physics, University of Tokyo, Komaba, Tokyo 153 (Japan)

Using the assumption of a partially conserved axial-vector current and the conservation law for the electromagnetic current, we rederive a low-energy theorem for the pion electroproduction. In contrast to the traditional approach, we include all effects of off-shell nucleons and pions. We parametrize the axial-vector current in its most general form and apply the minimal substitution prescription to obtain the radiative axial-vector vertex that is required for gauge invariance. We split the full radiative axial-vector vertex into the isolated-pole contribution, the minimal-coupling interaction, and the remainder. The Ward-Takahashi identities are translated into the constraints on the pion electroproduction amplitude. The rigorous low-energy theorem is obtained for the zero four-momentum pion electroproduction. It is found that the off-shell matrix elements of the axial-vector current affect the isolated-pole term and the gauge term so that the low-energy theorem is at variance with the standard one given in the literature.

• OSTI ID: 7199240
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 46:6; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

663420* -- Lepton-Induced Reactions & Scattering-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALGEBRAIC CURRENTS
AXIAL-VECTOR CURRENTS
BASIC INTERACTIONS
BOSONS
CURRENTS
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
HADRONS
INTERACTIONS
MESONS
NUCLEAR REACTIONS
PARTICLE PRODUCTION
PIONS
PSEUDOSCALAR MESONS