QCD corrections to e+ e- --> 4 jets

We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program ``Mercutio'', which can be used to calculate any infrared safe four-jet quantity in electron-positron annihilation at next-to-leading order.Comment: 4 pages, talk given at the UK Phenomenology Workshop on Collider Physics, Durham, 19-24 September 199

A subtraction scheme for computing QCD jet cross sections at NNLO: regularization of real-virtual emission

We present a subtraction scheme for computing jet cross sections in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbative QCD. In this second part we deal with the regularization of the real-virtual contribution to the NNLO correction.Comment: 32 pages, LaTeX file, uses pstrick

QCD Sum Rules for Heavy Flavors

We give a short review of QCD sum rule results for B and D mesons and Lambda_Q and Sigma_Q baryons. We focus mainly on recent developments concerning semileptonic B->pion and D->pion transitions, pion couplings to heavy hadrons, decay constants and estimates of the b quark mass from a baryonic sum rule, and the extraction of the pion distribution amplitude from CLEO data.Comment: 12 pages, LaTeX, Talk given by O.Yakovlev at the 4th Workshop on Continuous Advances in QCD, Minneapolis, May 12-14, 2000; to appear in the Proceeding

Subtraction terms for one-loop amplitudes with one unresolved parton

Fully differential next-to-next-to-leading order calculations require a method to cancel infrared singularities. In a previous publication, I discussed the general setup for the subtraction method at NNLO. In this paper I give all subtraction terms for electron-positron annihilation associated with one-loop amplitudes with one unresolved parton. These subtraction terms are integrated within dimensional regularization over the unresolved one-particle phase space. The results can be used with all variants of dimensional regularization (conventional dimensional regularization, the 't Hooft-Veltman scheme and the four-dimensional scheme).Comment: 27 page