Timeline for Gauge invariance (QED)

8 events

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Mar 9, 2015 at 2:41	comment	added	Ali Moh		intuitively the amplitude should be invariant under $\epsilon_\mu (p)\rightarrow \epsilon_\mu (p) + \alpha p_\mu$ because this represents a change in the longitudinal mode of the photon. See Srednicki Ch 67, or Zee II.7 or Weinberg 10.5
Mar 9, 2015 at 2:12	history	edited	Ali Moh	CC BY-SA 3.0	edited body
Mar 9, 2015 at 1:04	comment	added	PhilosophicalPhysics		By the way, Ali, you said that this Wrd was a consequence of gauge invariance. I am interested to know how is it that this is a consequence of that. If you have any reference you could link me to, I would appreciate it.
Mar 8, 2015 at 23:36	vote	accept	PhilosophicalPhysics
Mar 8, 2015 at 23:33	comment	added	Ali Moh		He is probably emphasizing that ward identity holds for the amplitude, and not necessarily for each of the feynman diagrams whose sum is the amplitude..
Mar 8, 2015 at 23:26	comment	added	PhilosophicalPhysics		Thank you Ali for your reply. But the author insisted that these conditions are met although the quantities in the equation $k_{1\nu}(A^{\mu\nu} + \tilde{A}^{\mu\nu})=0=k_{2\mu}(A^{\mu\nu} + \tilde{A}^{\mu\nu})$ each separately are all different from zero. Why would he say that if it is already a consequence of ward identity?
Mar 8, 2015 at 23:19	history	edited	Ali Moh	CC BY-SA 3.0	added 66 characters in body
Mar 8, 2015 at 23:13	history	answered	Ali Moh	CC BY-SA 3.0