Automatic computation of 1-loop amplitudes for multiparticle production at colliders

Automatic computation of 1-loop amplitudes for multiparticle production at colliders

Unitarity inspired methods have been proven to be efficient techniques for the evaluation of 1-loop amplitudes for multiparticle production processes at colliders. I will mainly focus on the OPP method, and on the evaluation of the Cut-Constructible and the Rational contributions to 1-loop amplitudes. I will discuss the implementation in Monte Carlo event generators, in particular the HELAC code, and I will briefly sketch the present potentialities and limits of the HELAC-NLO system, together with possible further extensions.