| Résume||(Work in progress with Michele Serra and Sebastian Krapp).
Let k be a field and G a totally ordered Abelian group. A Hahn field is an intermediate field K between k(G) (the fraction field of the group ring k[G], which we call the minimal Hahn field) and k((G)) (the field of generalised series, which we call the maximal Hahn field). While studying the group of valuation preserving automorphisms of K, we identified two crucial lifting properties of K which allow a fine description of that group. We still lack an understanding of the class of Hahn fields which do enjoy those properties. In the talk, we will discuss the properties, their relation to the automorphism group, and our current methods to obtain examples and counterexamples.|