No coupling of Photons with eletric fields

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Discussion Overview

The discussion centers around the interaction of photons with electric fields, specifically addressing the claim that photons do not couple with electric fields. Participants explore the concept of Delbruck scattering in Quantum Electrodynamics and its implications, as well as the conditions under which photon interactions may occur.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that photons do not couple with electric fields, referencing classical electromagnetic theory.
  • Others introduce the concept of Delbruck scattering, which involves weak higher-order photon-photon interactions due to virtual electron loops, and mention its experimental observation.
  • One participant questions the necessity of high photon energies for Delbruck scattering and inquires about the required magnitude of the Coulomb field.
  • Another participant suggests that quantum corrections to the Coulomb potential become significant at small distances, which may explain the need for higher photon energies to observe weak effects.
  • Concerns are raised about the feasibility of creating large electrostatic fields, with speculation that such fields could lead to electron-positron pair creation.

Areas of Agreement / Disagreement

Participants express differing views on the interaction of photons with electric fields, particularly regarding the conditions necessary for observable effects like Delbruck scattering. The discussion remains unresolved with multiple competing perspectives on the topic.

Contextual Notes

Limitations include the need for detailed mathematical analysis to fully understand the quantum corrections involved and the dependence on specific energy scales for photon interactions. The discussion also highlights challenges in finding relevant literature on the topic.

eintagsfliege
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I heard in the school a long time ago, that photons do not have a coupling with an electric field. Can someone explain it detailed? Does someone have good online literature?
Thanks in advance!
 
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eintagsfliege said:
I heard in the school a long time ago, that photons do not have a coupling with an electric field. Can someone explain it detailed? Does someone have good online literature?
I don't have time right now to explain it in detail but here's the basics...

Classically an electromagnetic field does not interact with itself.
But in Quantum Electrodynamics there is very weak higher-order
photon-photon scattering due to virtual electron loops. This
is called Delbruck scattering, and has been experimentally observed
via scattering of gamma rays off nuclei, iirc. I vaguely remember
that certain ultra-high-power lasers can also demonstrate the effect
somehow.

I don't know online references off the top of my head, but
Delbruck scattering is discussed in Greiner's textbook on
quantum electrodynamics.
 
Last edited:
Thank you for the
I read in several Publications that Delbruck-effect is the scattering of high-energy photons (MeV to GeV gamma rays) on a Coulomb-Field of a Nucleus.
My question is:
Why is it needed that the Photonenergies are this high?
Which magnitude is required for the Coulomb-Field?
Is it possible that an electrostatic field of a charged object (same scale) has the same effect?

It is hard to find some good literature online.
 
eintagsfliege said:
Why is it needed that the Photonenergies are this high?
A full answer to this requires working through the detailed math to
see what the quantum correction terms look like. Some people
explain it heuristically by noting that quantum corrections to
the usual Coulomb potential get stronger at small distances.
With higher energies you can probe smaller distances and
thus have more hope of seeing weak effects because of th
stronger EM field.

But I take such explanations with a grain of salt.

Which magnitude is required for the Coulomb-Field?
Is it possible that an electrostatic field of a charged object
(same scale) has the same effect?
I suspect that if you tried to create such a huge electrostatic
field it would tend to decay via electron-positron pair creation.
(This sort of thing happens in heavy ion collisions.)

It is hard to find some good literature online.
I know. A visit to the nearest University physics library is
probably needed.
 

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