Understanding the cancellation of ultraviolet and infrared singularities in perturbative quantum field theory is of central importance for the development and automation of various theoretical tools that make accurate predictions for observables at high-energy colliders. The loop-tree duality aims to find an efficient solution by treating loop and tree-level contributions under the same foot to achieve a local cancellation of singularities at the integrand level, and thus avoiding dimensional regularisation. In this talk, we exploit the causal properties of vacuum amplitudes in the loop-tree duality representation to present different applications to physical processes at higher orders.