Threshold Resummation of Soft Gluons in Hadronic Reactions -- An Introduction

I discuss the motivation for resummation of the effects of initial-state soft gluon radiation, to all orders in the strong coupling strength, for processes in which the near-threshold region in the partonic subenergy is important. I summarize the method of "perturbative resummation" and its application to the calculation of the total cross section for top quark production at hadron colliders. Comments are included on the differences between the treatment of subleading logarithmic terms in this method and in other approaches.Comment: 15 pages. latex, one figure. Invited paper to be published in the Proceedings of the Symposium on QCD Corrections and New Physics, Hiroshima, October 27 - 29, 199

Supersymmetry Explanation for the Puzzling Bottom Quark Production Cross Section

It has been known for a long time that the cross section for bottom-quark $b$ production at hadron collider energies exceeds theoretical expectations. An additional contribution from pair-production of light gluinos $\tilde{g}$, of mass 12 to 16 GeV, with two-body decays into bottom quarks and light bottom squarks $\tilde{b}$, helps to obtain a $b$ production rate in better agreement with data. The masses of the $\tilde{g}$ and $\tilde{b}$ are restricted further by the ratio of like-sign to opposite-sign leptons at hadron colliders. Constraints on this scenario from other data are examined, and predictions are made for various processes such as Upsilon decay into $\tilde{b}'s$.Comment: 10 pages, latex, 2 figures. Invited paper to be published in the Proceedings of the 9th International Symposium on Heavy Flavor Physics, Caltech, Pasadena, CA, September 10 - 13, 200

Supersymmetry Contribution to Bottom Quark Production at Hadron Colliders

A new contribution from pair-production of light gluinos, of mass 12 to 16 GeV, with two-body decays into bottom quarks and light bottom squarks, helps to obtain a bottom-quark production rate in better agreement with hadron collider data. The masses of the gluino and bottom squark are further restricted by the ratio of like-sign to opposite-sign leptons at hadron colliders. Constraints on this scenario from other data are examined and predictions are made.Comment: 4 pages, latex, 1 figure. Uses two-column style file ltwol.sty. To be published in the Proceedings of the Fourth International Workshop on B Physics and CP Violation, Ise-Shima, Japan, February 18 - 23, 200

Production of Prompt Photons

After a brief review of the production dynamics of prompt single photons in hadron collisions, I summarize a new QCD calculation of the transverse momentum distribution of continuum prompt photon pairs produced by QCD subprocesses, including all-orders soft-gluon resummation valid at next-to-next-to-leading logarithmic accuracy. Resummation is necessary to obtain reliable predictions, as well as good agreement with data from the Fermilab Tevatron, in the range of transverse momentum where the cross section is largest. Predictions are made for the Large Hadron Collider where the QCD diphoton continuum is shown to have a softer spectrum in transverse momentum than the Higgs boson signal.Comment: 5 pages, 2 figures, AIP style file. To be published in the Proceedings of the 9th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2006), Rio Grande, Puerto Rico, May 30 - June 3, 200

Light Bottom Squark Phenomenology

Agreement of theoretical calculations with the observed production rate of bottom quarks at hadron colliders is improved by the introduction of a contribution from pair-production of light gluinos, of mass 12 to 16 GeV, having two-body decays into bottom quarks and light bottom squarks with mass $\simeq 2$ to 5.5 GeV. Predictions are made for hadronic and radiative decays of the Upsilon states. In the limit of large $\tan\beta$, the dominant decay mode of the light scalar Higgs boson is into a pair of light bottom squarks that materialize as jets of hadrons.Comment: 3 pages, latex, no figures, uses espcrc2.sty style file. Paper to be published in the Proceedings of the 31st International Conference on High Energy Physics (ICHEP02), Amsterdam, July 24 - 31, 200