Compton Scattering of Quasi-Real Virtual Photons at LEP

TL;DR

This study measures the cross sections of Compton scattering involving quasi-real virtual photons at LEP energies, confirming QED predictions up to the highest energies tested, thus extending experimental validation of quantum electrodynamics.

Contribution

First measurement of Compton scattering cross sections involving virtual photons at energies up to 175 GeV, expanding the experimental validation of QED.

Findings

Cross sections agree with QED predictions across the energy range.

Extended the energy range of Compton scattering measurements to 175 GeV.

Provided the highest energy test of virtual photon Compton scattering to date.

Abstract

Compton scattering of quasi-real virtual photons, gamma e+- -> gamma e+-, is studied with 0.6fb-1 of data collected by the L3 detector at the LEP e+e- collider at centre-of-mass energies root(s')=189-209GeV. About 4500 events produced by the interaction of virtual photons emitted by e+- of one beam with e-+ of the opposite beam are collected for effective centre-of-mass energies of the photon-electron and photon-positron systems in the range from root(s')= 35GeV up to root(s')=175GeV, the highest energy at which Compton scattering was ever probed. The cross sections of the gamma e+- -> gamma e+- process as a function of root(s') and of the rest-frame scattering angle are measured, combined with previous L3 measurements down to root(s')~20GeV, and found to agree with the QED expectations.