Electron-positron pair creation by weak interaction?

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Discussion Overview

The discussion revolves around the mechanisms of electron-positron pair creation and annihilation, particularly focusing on the roles of weak and electromagnetic interactions. Participants explore whether electron-positron pairs can be produced via weak interactions or if this process is primarily governed by electromagnetic forces, as well as the nature of the particles involved in these interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether electron-positron pairs can be produced through weak interactions, similar to muon-antimuon pair production, or if this is exclusively an electromagnetic process.
  • Another participant confirms that electron-positron pairs can interact via virtual Z^0 bosons, indicating that this process is possible.
  • It is noted that the rarity of this process is due to the mass of the Z_0 boson, which suppresses the cross section for such interactions.
  • Some participants mention that while Z_0 exchange contributes to certain processes, it is often a small correction to the dominant photon-exchange model in low-energy scenarios.
  • The term "Bhabha scattering" is introduced as a technical term for the electron-positron scattering process, with details on how the Z contribution is suppressed at low energies but becomes significant at higher energies.
  • At center-of-mass energies around 90 GeV, Z exchange is suggested to dominate the interactions.
  • Historical context is provided regarding the Large Electron Positron (LEP) collider, which was designed to operate at energies conducive to Z_0 production.

Areas of Agreement / Disagreement

Participants express varying views on the dominance of weak versus electromagnetic interactions in the production of electron-positron pairs, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Limitations include the dependence on energy levels for the relevance of weak versus electromagnetic interactions and the specific conditions under which Z_0 exchange becomes significant.

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Hello,
Im trying to find out if, since an electron positron pair can anhillate to produce a muon-anti muon pair by the weak interaction, can the same thing occur for the production of an electron/anti-electron pair? Or would it just happen by the electromagnetic force? Or both, with the weak being supressed? And are the photons/ Z0 bosons involved real or virtual?
I feel as if I am asking a question I should know the answer to and being silly, but any help would be appreciated!
Thanks!
 
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e+e- -> e+e- via Virtual Z^0 is ok.
 
It's simply very rare because the mass of the Z_0 suppresses the cross section. I think some experiments do study contributions from Z_0 exchange in certain processes (maybe even e+e- scattering), as tiny corrections to a pure photon-exchange model.
 
Thanks, that's very helpful!
 
The technical term for this process is "Bhabha scattering":

http://en.wikipedia.org/wiki/Bhabha_scattering

If the electron and the positron are nearly at rest, Z contribution is significantly suppressed because the intermediate virtual Z is way off mass-shell. At high energies, both are important. At CM ~ 90 GeV, Z exchange will most likely dominate.
 
hamster143 said:
At CM ~ 90 GeV, Z exchange will most likely dominate.

Indeed, the old Large Electron Positron (LEP) collider was originally designed for a CM energy in that range, specifically to produce the Z_0.
 

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