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arXiv · 0803.4180

An Automated Implementation of On-Shell Methods for One-Loop Amplitudes

C. F. Berger·Z. Bern·L. J. Dixon·F. Febres Cordero·D. Forde·H. Ita·D. A. Kosower·D. Maitre
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Abstract

We present the first results from BlackHat, an automated C++ program for calculating one-loop amplitudes. The program implements the unitarity method and on-shell recursion to construct amplitudes. As input to the calculation, it uses compact analytic formulae for tree amplitudes for four-dimensional helicity states. The program performs all related computations numerically. We make use of recently developed on-shell methods for evaluating coefficients of loop integrals, introducing a discrete Fourier projection as a means of improving efficiency and numerical stability. We illustrate the numerical stability of our approach by computing and analyzing six-, seven- and eight-gluon amplitudes in QCD and comparing against previously-obtained analytic results.

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C. F. Berger, Z. Bern, L. J. Dixon, F. Febres Cordero, D. Forde, H. Ita, D. A. Kosower, D. Maitre. 2008-03-28. An Automated Implementation of On-Shell Methods for One-Loop Amplitudes. https://doi.org/10.1103/physrevd.78.036003

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