Tuesday, 20 November 2018 at 11:15, in Y16 G05 - Campus Irchel
Quantum field theory is poorly defined in four space-time dimensions due to unphysical configurations introduced by quantum corrections. These unphysical configurations lead to the proliferation of infinities that are usually regulated by modifying the dimensions of the space-time. In this talk we introduce the loop-tree duality (LTD) and the four-dimensional unsubtraction (FDU) formalisms.The LTD allows to rewrite loop scattering amplitudes in terms of connected tree-level dual amplitudes, and provides a very intuitive view over the origin of the IR and UV singularities and their interpretation in terms of causality. We also comment on its relation to the Feynman’s Tree Theorem. The FDU allows to perform the summation over soft and collinear degenerate states from virtual and real configurations by introducing a suitable mapping of momenta, then avoiding subtractions in the infrared in such a way that higher order perturbative calculations can directly be performed in four space-time dimensions. We illustrate the power of the formalism with benchmark physical examples.