Speaker
Description
It has been understood since the eighties that string theory amplitudes are in various aspects better organised than amplitudes in ordinary quantum field theory. One can try to exploit this fact either by representing field theory amplitudes as the infinite string-tension limit of string amplitudes (string-based formalism’’), or by representing them by worldline path integrals and evaluating those in a way analogous to string theory (string-inspired formalism’’). Here I review and compare both approaches with an emphasis on gravity amplitudes and aspects of Yang-Mills theory that bear a relevance for gravity such as color-kinematics duality and multi-particle states. A central role is played by the cycle-and-tail decomposed worldline integrands of the one-loop N-gluon amplitudes that have recently tuned out to provide a natural route to the construction of Berends-Giele currents in BCJ gauge for Yang-Mills theory as well as gravity.
