Restaurando a invariância de calibre em teorias não-abelianas de segunda classe

Abstract

Gauge theories are fundamental to the construction and understanding of the Standard Model of particle physics and of the fundamental interactions it describes. However, the explicit introduction of mass terms in models such as Yang–Mills violates gauge invariance and leads to systems described by second-class constraints within the Dirac formalism, thereby compromising critical aspects such as unitarity and perturbative renormalizability. The objective of this work is to extend the improved Gauge Unfixing formalism (IGU) to non-Abelian second-class models. The framework developed here is applied explicitly to the SU(N) massive Yang–Mills model and to the SU(2) Skyrme model. It is shown that, through a judicious choice of symmetry generators, the original phasespace variables can be mapped into gauge-invariant quantities. The results establish a direct correspondence between the IGU method, the generalized Stückelberg formalism, and the Dirac formalism, showing that the technique provides a robust tool for restoring gauge symmetry in regimes where interaction-mediating particles acquire mass. Furthermore, the method preserves the algebraic consistency and the physical interpretation of the system while leaving the number of physical degrees of freedom unchanged.