Uncovering the Mystery of Neutrino Interactions with Electromagnetic Force

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Discussion Overview

The discussion revolves around the interactions of neutrinos with electromagnetic forces, particularly focusing on their potential annihilation processes involving photons and W/Z bosons. Participants explore theoretical implications and the complexities of these interactions, including the role of magnetic moments and the conditions under which these annihilations might occur.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants propose that neutrinos, despite having no electric charge, can interact with magnetic fields due to their magnetic moment, leading to discussions about their annihilation with real photons.
  • Others argue that neutrinos do not couple directly to virtual photons but instead interact through W/Z boson loops, suggesting that annihilation occurs but with an extremely low probability due to tiny cross sections.
  • A participant questions whether annihilation would lead to photons or if it would primarily involve W bosons, seeking clarification on the interactions involved.
  • Some participants note that while annihilation to photons is theoretically possible, it requires off-mass-shell W/Z bosons, which significantly reduces the likelihood of such events.
  • There is a discussion about the absence of photon-Z interactions in the Standard Model, with some participants emphasizing the necessity of W bosons for photon production in annihilation processes.
  • One participant raises a hypothetical scenario involving a Z boson in the s-channel and an electron loop, prompting a response about the limitations imposed by the Landau-Yang theorem.
  • Another participant suggests that while the Landau-Yang theorem may suppress certain processes, it does not completely block them, particularly considering the implications of neutrino mass on angular momentum.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of neutrino interactions with electromagnetic forces, particularly concerning annihilation processes. The discussion remains unresolved, with differing opinions on the feasibility and mechanisms of these interactions.

Contextual Notes

Participants highlight the complexity of the interactions, including dependencies on the mass of neutrinos and the specific conditions required for annihilation processes. There are unresolved questions about the implications of the Landau-Yang theorem and the role of off-mass-shell particles in these interactions.

Upisoft
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While neutrinos have no electric charge they have magnetic moment and will interact with magnetic field causing precession of its spin.http://prl.aps.org/abstract/PRL/v45/i12/p963_1"

So if neutrinos can interact with virtual photons what makes it impossible to interact with real photons? What makes it impossible to annihilate in this way:
\nu + \bar{\nu} = \gamma + \gamma
 
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They don't couple to virtual photons directly. They go through a W/Z loop. And they do annihilate. They just happen to have an incredibly tiny cross section.
 
hamster143 said:
They don't couple to virtual photons directly. They go through a W/Z loop. And they do annihilate. They just happen to have an incredibly tiny cross section.
Meaning they will not annihilate to photons but to W/Z bosons? Did I get it correct?
 
They can annihilate to photons, I think. There's a number of different possible outcomes. The issue is that, since they don't couple to photons directly, any annihilation process will involve one or more seriously off-mass-shell W/Z bosons, and that means a very low probability of annihilation.
 
hamster143 said:
, any annihilation process will involve one or more seriously off-mass-shell W/Z bosons

W's, not Z's, if you want photons in the final state. There are no photon-Z interactions in the SM.
 
Vanadium 50 said:
W's, not Z's, if you want photons in the final state. There are no photon-Z interactions in the SM.

Ouch! What seemed to be improbable became almost impossible. At least for low energy neutrinos...

Thanks all for your answers.
 
Vanadium 50 said:
W's, not Z's, if you want photons in the final state. There are no photon-Z interactions in the SM.

can't you have something like a single Z in s channel and an electron loop at the end?
 
I don't think so. Landau-Yang theorem will block it.
 
Good point. But you can have three photons.

Also, will it block the process completely or just suppress it by some power of neutrino mass? I'm not very clear on that. It seems that, since neutrinos are massive, the Z boson could have nonzero angular momentum.
 
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