Validity of the equivalent-photon approximation for virtual photon-photon collisions

Journal Article · Sat Sep 01 00:00:00 EDT 1979 · Phys. Rev., D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.20.1057· OSTI ID:5996245

Carimalo, C; Kessler, P; Parisi, J

For virtual photon-photon collisions in electron storage rings we derive the equivalent-photon approximation from a helicity treatment and present it in two forms, involving, respectively (i) polarized transverse photons (''transverse-photon approximation'') and (ii) unpolarized ones (''Williams-Weizsaecker approximation''). We first postulate the conditions of validity of the approximation on the basis of analytic considerations, and then check them numerically in the case of the process ee ..-->.. ee..mu../sup +/..mu../sup -/. For this check we consider the completely differentiated cross section as far as approximation (i) is concerned, and in the case of approximation (ii), the cross section differentiated with respect to all variables except the azimuthal angles. Our results are given in the form of tables showing the lower and higher limit of the error involved in the approximation for a large variety of kinematic configurations (i.e., energy losses and scattering angles of both electrons). These tables are discussed in detail, and conclusions are drawn as to the applicability of the equivalent-photon approximation to future experiments to be performed with high-energy electron storage rings.

• Research Organization: Laboratoire de Physique Corpusculaire, College de France, Paris, France
• OSTI ID: 5996245
• Journal Information: Phys. Rev., D; (United States), Vol. 20:5
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ELECTRON-ELECTRON INTERACTIONS
PAIR PRODUCTION
MUONS
PHOTON-PHOTON INTERACTIONS
EQUIVALENT-PHOTON APPROXIMATION
DIFFERENTIAL CROSS SECTIONS
FEYNMAN DIAGRAM
GAUGE INVARIANCE
HELICITY
LORENTZ INVARIANCE
MATRIX ELEMENTS
POLARIZED BEAMS
STORAGE RINGS
VIRTUAL PARTICLES
BASIC INTERACTIONS
BEAMS
CROSS SECTIONS
DIAGRAMS
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
FERMIONS
INTERACTIONS
INVARIANCE PRINCIPLES
LEPTON-LEPTON INTERACTIONS
LEPTONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
645202* - High Energy Physics- Particle Interactions & Properties-Theoretical- Electromagnetic Interactions & Properties
645203 - High Energy Physics- Particle Interactions & Properties-Theoretical- Weak Interactions & Properties