Study of Multiphoton Final States and Tests of QED in e+e- collisions at \root(s) up to 209 GeV

TL;DR

This study measures multiphoton final states in electron-positron collisions up to 209 GeV, confirming QED predictions and setting limits on new physics phenomena such as excited electrons and extra dimensions.

Contribution

It provides precise measurements of e+ e- -> n gamma processes at high energies and tests QED with new limits on potential deviations and beyond Standard Model particles.

Findings

Total and differential cross sections agree with QED

Limits set on excited electrons and contact interactions

Constraints on extra space dimensions and excited leptons

Abstract

The process e+ e- -> n gamma with n>=2 is studied at centre-of-mass energies ranging from \root(s)=192 to 208 GeV. The data sample corresponds to a total integrated luminosity of 427 1/pb. The total and differential cross sections are found to be in agreement with the QED expectations. Using all the data collected with the L3 detector above the Z pole, limits on deviations from QED, excited electrons, contact interactions, extra space dimensions and excited spin-3/2 leptons are set.