Jordan François

We present a conservative generalisation of vector bundles associated to a principal bundle P. These are constructed via 1-cocycles of the action of the structure group H on P. The adapted notion of connection on P needed for the covariant derivation of sections of these bundles naturally extends Ehresmann connections. These sections and connections are, in the physics parlance, ``generalised gauge fields". As an illustration, we consider a way to obtain local twistors and their connection as end products of a gauge symmetry reduction of the conformal Cartan geometry: thus built, twistors and their connection appear as a clear instance of generalised gauge fields.