Abstract
The recently developed on-shell bootstrap for computing one-loop amplitudes in nonsupersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from nonstandard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through the use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining -gluon amplitudes in QCD. We give a recursive solution for the one-loop -gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude , as well as numerical results for , , and . We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.
10 More- Received 4 May 2006
DOI:https://doi.org/10.1103/PhysRevD.74.036009
©2006 American Physical Society