Measurement of the Running of the Fine-Structure Constant

TL;DR

This paper reports a measurement of how the effective fine-structure constant varies with energy scale using Bhabha scattering data from LEP, confirming theoretical predictions of its running at spacelike momentum transfers.

Contribution

It provides the first experimental measurement of the running of the fine-structure constant at high energies using LEP data, confirming quantum electrodynamics predictions.

Findings

Measured the change in alpha^-1 between -2.1 GeV^2 and -6.25 GeV^2 as 0.78 +/- 0.26.

Measured the change in alpha^-1 between -12.25 GeV^2 and -3434 GeV^2 as 3.80 +/- 1.29.

Results agree with theoretical expectations of the running of the fine-structure constant.

Abstract

Bhabha scattering data recorded at \sqrt{s}=189 GeV by the L3 detector at LEP are used to measure the running of the effective fine-structure constant for spacelike momentum transfers. The results are alpha^-1(-2.1 GeV^2) - alpha^-1(-6.25 GeV^2) = 0.78 +/- 0.26 alpha^-1(-12.25 GeV^2) - alpha^-1(-3434 GeV^2) = 3.80 +/- 1.29, in agreement with theoretical predictions.