# Dirac eqaution

1. Mar 19, 2013

Just to clarify in the dirac equation $(i\gamma^{\mu}\partial_{\mu} -m)\psi=0$

Is it equal to $(-i\gamma^{0}\partial_{0}+i\gamma^{i}\partial_{i} -m)\psi=0$ in (-,++++) notation?

2. Mar 19, 2013

### Bill_K

No, for a repeated index with one index up and one index down, just sum:

γμμ = γ00 + γ11 + γ22 + γ33

You only need to use the Minkowski metric if both indices are up, or both indices down:

ημνγμν = - γ00 + γ11 + γ22 + γ33

or ημνγμν = - γ00 + γ11 + γ22 + γ33