Achilleas Gitsis

α' (higher-derivative) corrections play a pivotal role in constructing a UV complete gravitational theory. They can also be translated as loop corrections in the language of σ-models. In this work, we present a systematic way of calculating said corrections, by moving to an extended space and extending its structure group to an infinite series of groups whose subgroup is the Double Lorentz group. Imposing certain torsion constraints and gauge fixing, we are able to reproduce the generalized Green-Schwarz transformations up to four derivatives present in the relative literature and a simple, universal expression for them that we conjecture to hold to all orders.