Efficient calculation of one-loop QCD amplitudes

We present the outline of a new and efficient technique for the calculation of loop amplitudes in a gauge theory. The technique is based on the technology of four-dimensional heterotic strings. We display here the application to the calculation of the one-loop corrections to gluon-gluon scattering, in ordinary dimensional regularization. We find complete agreement with the previous Feynman-diagram calculation of Ellis and Sexton.