An elementary electron-> electron + gamma process can not occur by itself in the vaccum because if we assume the photon invariant mass zero and the electron invariant mass positive, energy and momentum can not be conserved at the same time. The delta E may be computed and from the energy time incertinty principle we compute delta t, the maxium time allowed for the energy violation. After this time interval, whether the electron or the photon must interact further in order to have a process allowed in the vaccum.(adsbygoogle = window.adsbygoogle || []).push({});

If on the other hand we assume the momentum and the energy conservation simultaneously, the electron invariant mass positive and the photon invariant mass unknown, we compute the latter and find it pure imaginary. What would be the physical sense to this.

So, is energy conserved in elementary vertices or not?

Adrian Buzatu

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# Homework Help: Energy conservation in vertices in QED

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