Jet Evolution and the Underlying Event in Proton-Antiproton Collisions at 1.8 TeV

Rick Field and David Stuart
for the CDF collaboration
Abstract
The growth and development of "charged particle jets" produced in proton-antiproton collisions at 1.8 TeV are studied. A variety of "local" leading jet observables are compared with the QCD "hard scattering" Monte-Carlo models of Herwig, Isajet, and Pythia. The models describe quite well (although not completely) the multiplicity distribution of charged particles within the leading jet, the "size" of the leading jet, the radial flow of charged particles and transverse momentum around the leading jet direction, and the momentum distribution of charged particles within the leading jet. Also, a number of "global" observables are examined, where to fit the observable the QCD Monte-Carlo models have to describe correctly the entire proton-antiproton event structure. In particular, we study carefully the growth and structure of the "underlying event" in hard scattering processes. None of the models (with their default parameters) describe correctly all the properties of the underlying event.

Available in Postscript (PS), Adobe Acrobat (PDF), and Microsoft Word (DOC). Latex file coming soon! Analysis WEBsite.

Rick Field - March 12, 2000