gaugeprincipe
The gauge principle, or gauge invariance, is a foundational idea in modern theoretical physics. It holds that certain transformations of internal degrees of freedom do not change physical observables. When these transformations can vary with spacetime (local gauge invariance), the requirement of consistency leads to the introduction of gauge fields that mediate interactions between matter fields.
A classic example is electromagnetism, understood as a U(1) gauge theory. Demanding local phase invariance of
The principle generalizes to non-Abelian gauge theories, where the symmetry group is non-commutative (such as SU(2)
In the Standard Model of particle physics, gauge invariance under the group SU(3) × SU(2) × U(1)
Mathematically, gauge theories are described as connections on principal bundles, with gauge transformations reflecting changes of