Thank you. I'm still a little confused.
On page 9 in the notes http://www2.warwick.ac.uk/fac/sci/physics/current/teach/module_home/px435/dirac.pdf
it talks about the Feynman-Stuckelberg interpretation, where negative energy solutions represent positive energy antiparticles going forward in...
I am confused about the coupling of the Dirac equation to electromagnetism. The 4-current that is the source for Maxwell's equation that arises from the Lagrangian
\begin{equation}
\mathcal{L}=i\overline{\psi}\gamma^\mu(\partial_\mu+ieA_\mu)\psi-m\overline{\psi}\psi
\end{equation}
is...