2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/200270The so-called "soldering" procedure performed by A.M. Polyakov in [1] for a SL(2,R)-gauge theory is geometrically explained in terms of a Cartan connection on second order frames of the projective space RP^1. The relationship between a Cartan connection and the usual (Ehresmann) connection on a principal bundle allows to gain an appropriate insight into the derivation of the genuine " diffeomorphisms out of gauge transformations" given by Polyakov himself.Accepté pour publication dans Lett. Math. PhysMathematical PhysicsHigh Energy Physics - Theorytext