- #1
geoduck
- 258
- 2
Is there a proof or obvious reason why the vertex function is related to the current via:
[tex]S(p')\Gamma^\mu(p',p)S(p)=-\int \int dxdy e^{ipx}e^{-ipy} \langle T \psi(x) j^\mu(0) \bar{\psi}(y)\rangle [/tex]
In the free-field case one can see it's true. But the interacting case?
[tex]S(p')\Gamma^\mu(p',p)S(p)=-\int \int dxdy e^{ipx}e^{-ipy} \langle T \psi(x) j^\mu(0) \bar{\psi}(y)\rangle [/tex]
In the free-field case one can see it's true. But the interacting case?