Date of Award
Doctor of Philosophy
Physics and Astronomy
Jet production via the QCD Compton effect (gamma)q (--->) gq are inves- tigated by using Monte Carlo methods to simulate complete three jet events for photo-nucleon interactions. This process provides unique possibilities for jet studies because the incoming photon transfers its entire energy to the final state gluon and quark jets. We present a number of predictions for photons in the range of energies presently available up to Tevatron energies and find that the QCD Compton effect will dominate over vector meson dominance at large gluon transverse momenta;Also, we present a detailed analysis of single-particle and two-particle inclusive distributions in parton jets to provide a better understanding of the general features of hadron jet structures and to facilitate future jet measurements. To do this analysis, we formulate a model which unites the machinery of the KUV jet calculus with information on the probability for partons to form bound states;We calculate single-baryon inclusive distribution in gluon jets which may be useful in distinguishing a gluon jet from a quark jet. In the KUV jet calculus model, which has proved quite successful in earlier applications, the ratio of lambda hyperon ((LAMDA)) to proton (p) production remains constant with momentum fraction x in a gluon jet; whereas in a quark jet this ratio decreases with increasing x. It is suggested that the 3-gluon mode decay of quarkonium states can check this and other predictions;We study the fragmentation functions for quark and gluon break- up into two mesons, such as (pi)('+)(pi)('-), (pi)('+)k('-) and (pi)('+)(pi)('+), and show that within our model two complex and distinctive internal branching processes dominate the inclusive two-meson spectrum. The effects of leading quark, strangeness suppression, short-range charge compensation and scale breaking are predicted. We show a stronger Q('2) dependence of our model than in Willen's model. Similar characteristics of the limiting x (--->) 0 and x (--->) 1 behavior in single-baryon and two-meson production in parton jets are discussed. We also predict the inclusive two-meson cross sections in high energy electron-positron annihilation and deep inelastic lepton-nucleon;scattering which may provide a test of the universality of fragmentation functions for time-like and space-like processes; *DOE Report IS-T-1102. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Alexander H. Ng
Ng, Alexander H., "A theoretical study of parton fragmentation and evolution into hadrons " (1984). Retrospective Theses and Dissertations. 8201.