Mar 17, 2023 · The Dirac equation is a system of four linear homogeneous partial differential equations of the first order with constant complex coefficients that is invariant with respect to the general Lorentz group of transformations: $$ \gamma^{\alpha} \frac{\partial \psi}{\partial x^{\alpha}} - \mu \psi = 0, \qquad \alpha \in \{ 0,1,2,3 \}, $$ where