688 research outputs found
Antenna Showers with Hadronic Initial States
We present an antenna shower formalism including contributions from
initial-state partons and corresponding backwards evolution. We give a set of
phase-space maps and antenna functions for massless partons which define a
complete shower formalism suitable for computing observables with hadronic
initial states. We focus on the initial-state components: initial-initial and
initial-final antenna configurations. The formalism includes comprehensive
possibilities for uncertainty estimates. We report on some preliminary results
obtained with an implementation in the Vincia antenna-shower framework.Comment: 9 pages, 5 figure
The Five Gluon Amplitude and One-Loop Integrals
We review the conventional field theory description of the string motivated
technique. This technique is applied to the one-loop five-gluon amplitude. To
evaluate the amplitude a general method for computing dimensionally regulated
one-loop integrals is outlined including results for one-loop integrals
required for the pentagon diagram and beyond. Finally, two five-gluon helicity
amplitudes are given.Comment: (talk presented at DPF92), LaTeX, 6 pages, CERN-Th.6733/92,
SLAC-PUB-6012, UCLA/92/TEP/4
One-Loop Self-Dual and N=4 Super Yang-Mills
We conjecture a simple relationship between the one-loop maximally helicity
violating gluon amplitudes of ordinary QCD (all helicities identical) and those
of N=4 supersymmetric Yang-Mills (all but two helicities identical). Because
the amplitudes in self-dual Yang Mills have been shown to be the same as the
maximally helicity violating ones in QCD, this conjecture implies that they are
also related to the maximally helicity violating ones of N=4 supersymmetric
Yang-Mills. We have an explicit proof of the relation up to the six-point
amplitude; for amplitudes with more external legs, it remains a conjecture. A
similar conjecture relates amplitudes in self-dual gravity to maximally
helicity violating N=8 supergravity amplitudes.Comment: 14 pages, TeX, three figures, two new references adde
EFFICIENT ANALYTIC COMPUTATION OF HIGHER-ORDER QCD AMPLITUDES
We review techniques simplifying the analytic calculation of one-loop QCD
amplitudes with many external legs, for use in next-to-leading-order
corrections to multi-jet processes. Particularly useful are the constraints
imposed by perturbative unitarity, collinear singularities and a
supersymmetry-inspired organization of helicity amplitudes. Certain sequences
of one-loop helicity amplitudes with an arbitrary number of external gluons
have been obtained using these constraints.Comment: Talk given at Beyond the Standard Model IV, December 13-18 1994, Lake
Tahoe, CA. Latex, 4 pages, no figures
Cross-Order Relations in N=4 Supersymmetric Gauge Theories
The anti-de Sitter/conformal field theory duality conjecture raises the
question of how the perturbative expansion in the conformal field theory can
resum to a simple function. We exhibit a relation between the one-loop and
two-loop amplitudes whose generalization to higher-point and higher-loop
amplitudes would answer this question. We also provide evidence for the first
of these generalizations.Comment: 6 pages, talk given at the 3rd International Symposium on Quantum
Theory and Symmetries, Cincinnati, OH, Sept 10-14, 2003; v2: Mispositioned
figure in eqn. 1 fixe
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