Gauge freedom in quantum particle physics is shown to arise in a natural way
from the geometry of two-spinors (Weyl spinors). Various related mathematical
notions are reviewed, and a special ansatz of the kind "the system defines the
geometry" is discussed in connection with the stated results.Comment: Elaboration of work presented at the workshop "Geometry and Quantum
Theories", held in Florence, June 10-11, 2013, on the occasion of the
retirement of Luigi Mangiarotti and Marco Modugno, International Journal of
Geometric Methods in Modern Physics (2014
