- #1
eoghan
- 207
- 7
Hi!
In some texts (Sakurai - advanced qm and others) I found this expression for the lagrangian of an em field:
[tex]
L=F_{\mu \nu}F_{\mu \nu}
[/tex]
but I'm a bit confused... L must be a Lorentz invariant, so I would write instead:
[tex]
L=F_{\mu \nu}F^{\mu \nu} \;\;
[/tex]
Which form is the correct one? Or are they both correct?
In some texts (Sakurai - advanced qm and others) I found this expression for the lagrangian of an em field:
[tex]
L=F_{\mu \nu}F_{\mu \nu}
[/tex]
but I'm a bit confused... L must be a Lorentz invariant, so I would write instead:
[tex]
L=F_{\mu \nu}F^{\mu \nu} \;\;
[/tex]
Which form is the correct one? Or are they both correct?