Relations between the Worldline Quantum Field Theory and scattering amplitudes for particles with spin

Abstract: The Worldline Quantum Field Theory (WQFT) has proven to be an efficient tool for calculating observables in gravitational wave physics. In contrast to other QFT-based techniques in the realm of gravitational wave physics, it makes the classical limit very apparent. However, a natural question remains: How does it relate to ordinary quantum field theories that we know from particle physics? This question will be addressed by extending existing approaches to a description including spin. Furthermore, it will be explicitly shown that the WQFT can retain quantum contributions by summing up infinite towers of worldline loops.