Measurement of the Low-x Behaviour of the Photon Structure Function F2-gamma

TL;DR

This paper reports new measurements of the photon structure function F2-gamma at very low x values using OPAL data from LEP, employing advanced Monte Carlo models and unfolding techniques to reduce systematic errors.

Contribution

It presents the first measurements of F2-gamma at very low x with improved methods that lower model dependence and systematic uncertainties.

Findings

Extended the x range to lower values than previous measurements.

Implemented multi-variable unfolding to improve accuracy.

Reduced systematic errors compared to earlier analyses.

Abstract

The photon structure function F2-gamma(x,Q**2) has been measured using data taken by the OPAL detector at centre-of-mass energies of 91Gev, 183Gev and 189Gev, in Q**2 ranges of 1.5 to 30.0 GeV**2 (LEP1), and 7.0 to 30.0 GeV**2 (LEP2), probing lower values of x than ever before. Since previous OPAL analyses, new Monte Carlo models and new methods, such as multi-variable unfolding, have been introduced, reducing significantly the model dependent systematic errors in the measurement.