コロキウムのお知らせ

We will introduce modern methods of calculation of scattering amplitudes of gauge theories at one loop, beyond the Feynman diagrams and based on the generalized unitarity. The new trends in amplitudes computations are at one loop based on the precise knowledge of an integral basis (master) in which to expand a general color stripped amplitude. In particular, the knowledge of the singularities of such basis allows to obtain the coefficients of those master integrals as a rational function of spinors products expressed in terms of the kinematical labels of the external legs. Working in dimensional regularization we will focus our attention on the calculation of the so called rational terms of an amplitude, arising because the cancellations of poles against small deviations from the four dimensional limit.