Sources ofbquarks at the Fermilab Tevatron and their correlations

Abstract

The leading-logarithm order QCD hard scattering Monte Carlo models of HERWIG, ISAJET, and PYTHIA are used to study the sources of b quarks at the Fermilab Tevatron. The reactions responsible for producing b and $\overline{b}$ quarks are separated into three categories: flavor creation, flavor excitation, and parton-shower or fragmentation. Flavor creation corresponds to the production of a $b\overline{b}$ pair by gluon fusion or by annihilation of light quarks, while flavor excitation corresponds to a b or $\overline{b}$ quark being knocked out of the initial state by a gluon or a light quark or antiquark. The third source occurs when a $b\overline{b}$ pair is produced within a parton shower or during the fragmentation process of a gluon or a light quark or antiquark (includes gluon splitting). The QCD Monte Carlo models indicate that all three sources of b quarks are important at the Tevatron and when combined they qualitatively describe the inclusive cross-section data. Correlations between the b and $\overline{b}$ quark are very different for the three sources and can be used to isolate the individual contributions.