Setting the jet energy scale for the ZEUS calorimeter

TL;DR

This paper presents an improved method for calibrating jet energy measurements in the ZEUS detector, combining tracking, calorimeter data, and simulation to achieve a 1% uncertainty in the jet energy scale.

Contribution

It introduces a dual-method correction procedure for jet energy scale calibration, enhancing accuracy and reliability in ZEUS measurements.

Findings

Achieved a jet energy scale uncertainty of +/- 1%.

Validated correction methods with data and simulation comparisons.

Improved resolution of reconstructed kinematic variables.

Abstract

A much improved determination of the transverse energy of jets has been carried out in ZEUS, using a correction procedure based on two independent methods. The first is based on a combination of tracking and calorimeter information which optimises the resolution of reconstructed kinematic variables. The conservation of energy and momentum in neutral current deep inelastic e^+p scattering events is exploited to determine the energy corrections by balancing the kinematic quantities of the scattered positron with those of the hadronic final state. The method has been independently applied to data and simulated events. The second method uses calorimeter cells as inputs to the jet algorithm. Simulated events are then used to provide a correction for the energy loss due to inactive material in front of the calorimeter. A detailed comparison of the jet transverse energy and the transverse energy of tracks in a cone around the jet provides the final correction. This procedure relies on an accurate simulation of charged tracks and so is less reliant on simulating the energy loss of neutral particles in inactive material. Final comparisons of the data and simulated events for both methods allow an uncertainty +/- 1% to be assigned to the jet energy scale.