Space-time origin of gauge symmetry

In this work, by a first principles calculation, we show that quantum states describing massive relativistic free spinning particles obey kinematical conditions whose origin can be traced to parity as a good quantum number. These conditions are at the root of the equations of motion and of the constraints satisfied by the corresponding fields. In the massless limit, well defined parity is lost but a symmetry emerges related to arbitrary changes in the unphysical parity components. It is shown that this emergent symmetry is the celebrated gauge symmetry.

Automated summary

In this work, it is shown by a first principles calculation that quantum states describing massive relativistic free spinning particles obey certain kinematical conditions, which can be traced back to parity as a good quantum number. These conditions are fundamental to the equations of motion and the constraints satisfied by the corresponding fields. In the massless limit, a well-defined parity is lost but a symmetry related to arbitrary changes in the unphysical parity components emerges, and it is demonstrated that this emergent symmetry is the celebrated gauge symmetry.