Real-photon spectral weight functions, imaginary part of vacuum polarization, and electromagnetic vertices

Journal Article · Fri Dec 15 04:00:00 EST 1978 · Phys. Rev., D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.18.4617· OSTI ID:6416633

Chahine, C

We introduce the concept of a real-photon spectral weight function for any cross section involving charged particles as a simple approximation taking into account the soft part of photon emission to all orders in perturbation theory. The spectral weight function replaces the energy-momentum conservation delta function in the elastic cross section. The spectral weight function is computed in closed form in space time and in the peaking approximation in momentum space. We apply the spectral weight function description to the imaginary part of vacuum polarization ImPP and to electron-proton scattering. We derive a spectral representation for ImPP and compare its content with the known fourth-order result, showing in particular the identity of the soft and peaking approximations in lowest order. The virtual-photon radiative corrections are discussed in part, with emphasis on the threshold behavior of the vertex functions. A relativistic generalization of the electric nonrelativistic vertex function is given, whose asymptotic behavior is appropriate to use in conjunction with the spectral weight function.

• Research Organization: Department of Physics, Brandeis University, Waltham, Massachusetts 02154
• OSTI ID: 6416633
• Journal Information: Phys. Rev., D; (United States), Journal Name: Phys. Rev., D; (United States) Vol. 18:12; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

645202* -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- Electromagnetic Interactions & Properties
645203 -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- Weak Interactions & Properties
645400 -- High Energy Physics-- Field Theory
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CONSERVATION LAWS
CROSS SECTIONS
DELTA FUNCTION
ELASTIC SCATTERING
ELECTRON-NUCLEON INTERACTIONS
ELECTRON-PROTON INTERACTIONS
ELEMENTARY PARTICLES
FUNCTIONS
INTERACTIONS
LEPTON-BARYON INTERACTIONS
LEPTON-HADRON INTERACTIONS
LEPTON-NUCLEON INTERACTIONS
MASSLESS PARTICLES
PARTICLE INTERACTIONS
PERTURBATION THEORY
PHOTONS
SCATTERING
SPACE-TIME
SPECTRAL FUNCTIONS
VACUUM POLARIZATION
VERTEX FUNCTIONS