Speaker
Description
In this talk we present a new approach called Local Analytic Sector subtraction, recently proposed in Turin, which aims to efficiently tackled the problem of the cancellation of infrared singularities in order to perform multi-parton NLO (and beyond) QCD calculations.
The actual cancellation is basically achieved subtracting from the real radiation scattering amplitude simple counterterms (set of functions that locally reproduce all its singular limits) and adding them back to the virtual contribution once integrated on the phase space of the unresolved radiations. Taking advantage of every degree of freedom left in the definition of these functions, the scheme implementation incorporates key insights from NLO successful subtraction methods, as the FKS partition of the radiative phase space into sectors and the remapping of the kinematics of momenta in the Born-level amplitudes introduced by Catani-Seymour, followed by the consequent factorization of the unresolved phase space. Thanks to this, the Local Analytic Sector subtraction manages to achieve the locality, the simplicity of calculation and the structure minimality that make it an ideal candidate for the formulation of a universal analytic scheme for the cancellation of infrared divergences in perturbative QCD.
At NLO the subtraction scheme has been recently generalized to the treatment of initial-state radiation, while at NNLO a proof of concept that applies to massless final-state QCD radiation only has been presented.