No abstract

The pole mass of a heavy quark is ambiguous by an amount of order ⌳ QCD . We show that the heavy-quark potential, V(r), is similarly ambiguous, but that the total static energy, 2M pole ϩV(r), is unambiguous when expressed in terms of a short-distance mass. This implies that the extraction of a short-distance mass from the quarkonium spectrum is free of an ambiguity of order ⌳ QCD , in contrast with the pole mass.

We introduce a new color decomposition for multi-parton amplitudes in QCD, free of fundamental-representation matrices and structure constants. This decomposition has a physical interpretation in terms of the flow of color, which makes it ideal for merging with shower Monte-Carlo programs. The color-flow decomposition allows for very efficient evaluation of amplitudes with many quarks and gluons, many times faster than the standard color decomposition based on fundamental-representation matrices. This will increase the speed of event generators for multi-jet processes, which are the principal backgrounds to signals of new physics at colliders.

We study the production and detection of the standard-model Higgs boson at the Fermilab Tevatron. The most promising mode is W H and Z H associated production followed by leptonic decay of the weak vector bosons and H -i bb. It may be possible to detect a Higgs boson of mass m H = 60-80 GeV with 1000 pb-l of integrated luminosity. We also study the signature for a nonstandard "bosonic" Higgs boson whose dominant decay is to two photons. A signal is easily established with 100 pb-' in the W H and Z H channels, with the weak vector bosons decaying leptonically or hadronically, up to n z H = 100 GeV.PACS number(s): 14.80.Bn, 13.85.Qk