Comparison of bottom-quark production rates in ISAJET with a full QCD 2→3 calculation

High-statistics samples of events have been generated with the isajet Monte Carlo simulation program in a study of bottom-quark production in proton-antiproton collisions at $\sqrt{s}=630\mathrm{} \mathrm{and} 1800$ GeV. These samples include lowest-order QCD production, flavor excitation, and gluon splitting contributions. Both Eichten-Hinchliffe-Lane-Quigg and Diemoz-Ferroni-Longo-Martinelli structure functions have been used. The integral transverse-momentum distribution ${\sigma }_T(p_{T,b}>p_{T,min})$ is presented for each data set. Results are compared to a full analytical next-to-leading-order calculation of Nason, Dawson, and Ellis. We find that isajet cross sections at large $p_T$ are greater than the results obtained in the analytical calculation. In addition, the ratio of the full cross section to the lowest-order result ($K$ factor) can be as large as a factor of 2 greater than the analytical result, depending on $\sqrt{s}$ and $p_T$. We discuss the implications of these overestimates that relate to the phenomenology of heavy-flavor production, notably searches for the top quark.