I do know that nowadays dirac equation is interpreted as field-theoretic equation, not as particle equation.
But is there any sense that dirac equation can still be said to have wavefunction that gives us probability density of a particle at some location that can be verified with some form of experiment?
I do know that in real-life experiment, we verify QFT theories by scattering experiments, with transition probability checked using S-matrix. So the question is about whether probability density in location basis can still have experimental/observational meaning in dirac equatio, and not just historical coincidence of Dirac trying to derive positive-definite probability density for a particle in relativistic setting.
