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Title: Soft-photon expansion and soft-photon theorem

Abstract

The question of the existence of the soft-photon expansion and its connection with the derivation of the soft-photon theorem is studied. We find that the soft-phonon expansion does not necessarily exist for all possible bremsstrahlung cross sections, and if such an expansion does not exist for some types of cross section, then the soft-photon theorem cannot be derived for them. We define two different classes of bremsstrahlung cross section for our study, which we call the H-type cross section and the R-type cross section. We find that the R-type cross section can be expanded in powers of k (photon momentum) with all coefficients of the expansion which are independent of k, while the H-type cross section can only have an expansion whose coefficients are all functions of k. Moreover, we have shown that those coefficients which are functions of k must necessarily contain off-shell parameters. Therefore, we conclude that the soft-photon expansion exists and hence the soft-photon theorem can be derived only for the R-type cross section. This strongly implies that the R-type cross section is to be preferred for the study of bremsstrahlung processes.

Authors:
Publication Date:
Research Org.:
Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210
OSTI Identifier:
6773083
Resource Type:
Journal Article
Journal Name:
Phys. Rev., D; (United States)
Additional Journal Information:
Journal Volume: 18:9
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BREMSSTRAHLUNG; CROSS SECTIONS; ELASTIC SCATTERING; PION-PROTON INTERACTIONS; SERIES EXPANSION; ELECTROMAGNETIC RADIATION; HADRON-HADRON INTERACTIONS; INTERACTIONS; MESON-BARYON INTERACTIONS; MESON-NUCLEON INTERACTIONS; PARTICLE INTERACTIONS; PION-NUCLEON INTERACTIONS; RADIATIONS; SCATTERING; 645202* - High Energy Physics- Particle Interactions & Properties-Theoretical- Electromagnetic Interactions & Properties

Citation Formats

Liou, M K. Soft-photon expansion and soft-photon theorem. United States: N. p., 1978. Web. doi:10.1103/PhysRevD.18.3390.
Liou, M K. Soft-photon expansion and soft-photon theorem. United States. doi:10.1103/PhysRevD.18.3390.
Liou, M K. Wed . "Soft-photon expansion and soft-photon theorem". United States. doi:10.1103/PhysRevD.18.3390.
@article{osti_6773083,
title = {Soft-photon expansion and soft-photon theorem},
author = {Liou, M K},
abstractNote = {The question of the existence of the soft-photon expansion and its connection with the derivation of the soft-photon theorem is studied. We find that the soft-phonon expansion does not necessarily exist for all possible bremsstrahlung cross sections, and if such an expansion does not exist for some types of cross section, then the soft-photon theorem cannot be derived for them. We define two different classes of bremsstrahlung cross section for our study, which we call the H-type cross section and the R-type cross section. We find that the R-type cross section can be expanded in powers of k (photon momentum) with all coefficients of the expansion which are independent of k, while the H-type cross section can only have an expansion whose coefficients are all functions of k. Moreover, we have shown that those coefficients which are functions of k must necessarily contain off-shell parameters. Therefore, we conclude that the soft-photon expansion exists and hence the soft-photon theorem can be derived only for the R-type cross section. This strongly implies that the R-type cross section is to be preferred for the study of bremsstrahlung processes.},
doi = {10.1103/PhysRevD.18.3390},
journal = {Phys. Rev., D; (United States)},
number = ,
volume = 18:9,
place = {United States},
year = {1978},
month = {11}
}