Measurement of QCD jet broadening in pp̅ collisions at √s = 1.8 TeV

Abstract

A measurement of the QCD jet-broadening parameter <Q_T> is described for high-E_T jet data in the central calorimeter of the Collider Detector at Fermilab. As an alternate approach to clustering analysis, this method involves the use of a global event parameter which is free from the ambiguities associated with the definition and separation of individual clusters. The parameter Q_T is defined as the scalar sum of the transverse momentum perpendicular to the transverse thrust axis. Parton-level QCD predictions are made for <Q_T> as a function of E_T, the total transverse energy in the events, and suggest that a measurement would show a dependence on the running of the strong coupling constant α_s. Comparisons are made to first-order QCD parton-level calculations, as well as to fully evolved and hadronized leading-log simulations. The data are well described by the QCD predictions.