Determination of the LEP Beam Energy using Z Recoil Events

TL;DR

This paper presents a method to verify LEP beam energy using Z recoil events, confirming the accuracy of existing measurements and reducing uncertainties in W mass determination.

Contribution

It introduces a cross-check technique for LEP beam energy using Z recoil events, providing a validation of the LEP energy measurements.

Findings

No significant deviation found in beam energy from Z recoil analysis

Results agree with LEP energy group measurements

Method enhances confidence in W mass measurements

Abstract

The precise knowledge of the beam energy, E_beam, at the LEP collider is important to reduce the systematic uncertainty on the W mass. The measurements by the LEP energy group can be cross checked using Z recoil events. Preliminary results of the four LEP experiments ALEPH, DELPHI, L3, and OPAL are presented. The combination of the results shows no significant deviation of the E_beam value obtained using Z recoil events from the measurement by the LEP energy group.