CERN Accelerating science

Published Articles
Title	Photon radiation from quarks at LEP
Related title	Photon radiation from quarks at LEP.
Author(s)	Thompson, J C (Rutherford)
Publication	1994
Number of pages	6
In:	29th Rencontres de Moriond : Hadronic Session, Méribel-lès-Allues, France, 19 - 26 Mar 1994, pp.45-50
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LEP ; ALEPH CERN LEP ; OPAL
Abstract	Earlier measurements at LEP of isolated hard photons in hadronic zo decays attributed to radiation from primary quark pairs, have been extended in the ALEPH experiment to include their production inside hadron jets. Events are selected where all particles combine "democratically" to form 2 hadron jets, one of which contains a photon with a fractional energy z � 0. 7. After the statistical subtraction of events arising from non-prompt photons, the quark-to-photon fragmentation function, D(z), is extracted directly from the measured prompt production rate. Taking into account the perturbative contributions to D(z) obtained in an O(aa,) MS renormalisation scheme enables the unknown non-perturbative component of D(z) to be determined at high z. This measurement provides a better description of quark bremmstrahlung than hitherto employed in high energy hadron-hadron collisions. A updated analysis is also presented from OPAL of comparisons between 1-jet plus isolated photon rates and different QCD matrix element calculations.

Corresponding record in: Inspire