Test of non-commutative QED in the process e+e- -> gamma gamma at LEP

TL;DR

This paper tests non-commutative QED predictions against e+e- -> gamma gamma data from LEP, setting the first experimental limits on the theory's energy scale and exploring potential time-dependent signals.

Contribution

It provides the first experimental limits on non-commutative QED using collider data and examines how angular distributions can constrain the model parameters.

Findings

Lambda_NC > 141 GeV at 95% confidence level for all eta and xi

Angular distributions used to set limits on non-commutative QED parameters

Time dependence of cross-section could reveal the model parameter xi if a signal is detected

Abstract

Non-commutative QED would lead to deviations from the Standard Model depending on a new energy scale Lambda_NC and a unique direction in space defined by two angles eta and xi. Here in this analysis eta is defined as the angle between the unique direction and the rotation axis of the earth. The predictions of such a theory for the process e+e- -> gamma gamma are evaluated for the specific orientation of the OPAL detector and compared to the measurements. Distributions of the polar and azimuthal scattering angles are used to extract limits on the energy scale Lambda_NC depending on the model parameter eta. At the 95% confidence level Lambda_NC is found to be larger than 141 GeV for all eta and xi. It is shown that the time dependence of the total cross-section could be used to determine the model parameter xi if there were a detectable signal. These are the first limits obtained on non-commutative QED from an e+e- collider experiment.