LBL-23738Data from the Time Projection Chamber at the SLAC storage ring PEP have been used to study the inclusive production of charged hadrons. Particles were identified by simultaneous dE/ dx and momentum measurements. Cross sections and particle fractions for 1r±, k±, and p(p) are given as a function of several variables. Predictions of various hadronization models are compared to the data. A comparison is made with other fragmentation processes.
This work is supported by the United States Department of Energy underContract DE-AC03-76SF00098.
AcknowledgementsI would like to thank my advisor, Werner Hofmann, for the many things he has taught me and for the useful advice he has given me in doing my analysis. I would also like to thank Werner, Gerson Goldhaber, and Samuel Markowitz for their comments as members of my thesis committee. Of course, this thesis would not be possible without the efforts of many people in the collaboration who played various roles in building the detector and making it work, and who offered me many helping hands. Their efforts are much appreciated, especially those of Hiro Yamamoto, Gerry Lynch, Philippe Eberhard, and Ron Ross.
IntroductionThe nature of the strong interactions has been a concern since the 1930's when people tried to understand the forces that held nuclei together. Today it is believed that the problem is solved in principle: strong interactions are described by the theory of quantum chromodynamics or QCD. Explicit solutions to many problems, however, can not be given using QCD because of mathematical complexities. Of particular interest is the fragmentation of quarks into jets of hadrons under the influence of color confinement forces, because it is one of the fundamental phenomena of high energy physics. Unfortunately, current mathematical techniques are not powerful enough to solve the QCD equations governing quark fragmentation. In the absence of explicit solutions, fragmentation models have been developed, and insight into QCD is obtained by the agreement of certain models with experimental data. The reaction e+ e--+ hadrons provides a very clean environment to study quark fragmentation and to establish a rich data base against which fragmentation models as well as particle production in other reactions can be compared. This thesis provides a coherent set of inclusive charged pion, kaon, and proton cross sections and the associated particle fractions in commonly used variables such as rapidity, Feynman x, transverse momentum, etc. These results should be of interest to model builders and others working in all aspects of fragmentation physics. Predictions of various hadronization models of current interest are compared to the data. Comparisons are also made between fragmentation in e+e-annihilation and fragmentation in other processes. The thesis starts with a review of e+e-annihilation in Chapter 2. Different fragmentation models of current interest are also discussed. In Chapter 3 the Time Projection Chamber (TPC) detector used for collecting the data i...