Recent content by dfttheory

I just realized that the discussions related to this may contain some of what I am looking for. I would be interested in any additional discussion about this. Thanks!

So, I have a basic/general question here. I understand that, for example, the QED Langrangian has U(1) gauge symmetry. I also understand that this means (when you have written the Lagrangian with the covariant derivative) that if you transform the wavefunction (\psi \rightarrow e^{i \theta (x)}...