Quantum corrections without loops and in four space-time dimensions

Germán Rodrigo

Instituto de Física Corpuscular

 

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 a new regularization scheme, called four-dimensional unsubtraction (FDU), which is based on the loop-tree duality (LTD). The LTD allows to rewrite loop scattering amplitudes in terms of tree-level dual amplitudes, and provides a very intuitive view over the origin of the singularities and their interpretation in terms of causality.  The FDU allows to perform the summation over degenerate states by introducing a suitable mapping of momenta, 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, the proof of the universality of the Higgs boson interactions, and the direct application to asymptotic expansions.