Momentum exchange theory of photon diffraction

Two-photon Exchange in Electron-proton Elastic Scattering: Theory Update

Recent theoretical developments in the studies of two-photon exchange effects in elastic electron-proton scattering are reviewed. Two-photon exchange mechanism is considered a likely source of discrepancy between polarized and unpolarized experimental measurements of the proton electric form factor at momentum transfers of several GeV. This mechanism predicts measurable effects that are current...

Photon-exchange processes at hadron colliders as a probe of the dynamics of diffraction

The rich structure of photon-exchange processes at hadron colliders is studied. We discuss central vector meson production (pp → p + J/ψ + p), W production (pp → p+W+X) and μ+μ− production. Each process has distinct, and large, soft pp rescattering effects, which can be directly observed by detecting the outgoing protons. This allows a probe of the optical density of the proton, which plays a c...

High Momentum Particle and Jet Production in Photon-photon Collisions *

Jet and particle production have been studied in collisions of quasi-real photons collected during the LEP2 program. OPAL and DELPHI report good agreement of NLO perturbative QCD with the measured differential di-jet cross sections, which reach a mean transverse energy of the di-jet system of 25GeV. L3, on the other hand, finds drastic disagreement of the same calculation with single jet produc...

Diffraction Theory

Photon orbital angular momentum: problems and perspectives

Electromagnetic fields can carry, besides energy, linear and angular momentum. The exchange of linear momentum with matter produces forces due to radiation pressure. That comet tails point away from the Sun because light carries linear momentum was first suggested by Kepler. A complete account of radiation pressure was developed by Poynting in 1905 in terms of electromagnetic linear momentum de...