Left/right handed electrons - what's the difference?

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Discussion Overview

The discussion revolves around the differences between left-handed and right-handed electrons, focusing on their chirality, implications in quantum field theory (QFT), and whether these distinctions have practical significance or observable consequences. Participants explore theoretical aspects and potential experimental observations related to these concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants explain that left and right-handed refers to the chirality of an electron, with right-handed chirality indicating that the spin and momentum point in the same direction, while left-handed indicates the opposite.
  • One participant questions how the distinction between left-handed and right-handed electrons manifests in practical terms, asking if two electrons in a box could be distinguished based on their chirality.
  • Another participant asserts that no massive free particles have definite helicity and claims that a pure left-handed electron does not exist as a free particle, while noting that the weak nuclear force couples only to the left-handed component of the electron.
  • There is mention of the Higgs mechanism and the breakdown of symmetry as relevant to the mass of electrons and their chirality, suggesting a complex relationship between these concepts.

Areas of Agreement / Disagreement

Participants express differing views on the existence and significance of left-handed and right-handed electrons, with some asserting theoretical distinctions while others challenge the practical implications and existence of pure left-handed electrons as free particles. The discussion remains unresolved regarding the observable consequences of these distinctions.

Contextual Notes

Limitations include the dependence on definitions of chirality and helicity, as well as unresolved questions about the practical observability of left-handed versus right-handed electrons in experimental settings.

Rhizomorph
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Can someone explain to me in layman's terms what the difference between a left and right handed electron is. Have we encountered right handed electrons? Do they still have the same mass, charge, lifetime, etc? So what is the difference, and is this difference theoretical or has it been observed? In other words, is there any real reason to draw a distinction between the two?

Rhizomorph.
 
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Left and right handed refers to the chirality of an electron. Right handed chirality means that the spin and momentum of the electron point in the same direction. Left handed means opposite direction of spin and momentum. This distinction is made because these two chiralities refer to two fundamentally different components of the elektron wave function. In QFT a mass mixes these two components and that is why elektrons doe not have mass as an elementary particle. Mass is generated by the Higgs-mechanism and the breakdown of symmetry of the vacuum-states.
 
"these two chiralities refer to two fundamentally different components of the elektron wave function"

Then I guess my question is how does that manifests itself in any meaningfull way? If, theoretically, you had 2 electrons in a box, one left-handed, one right-handed, is there any way to distinguish between the two?
 
No massive free particles have definite heliticity (it is not conserved during free particle propagation), so there is no such thing as a left-handed electron. However, using projection operators, we can split the electron wavefunction into left-handed and right-handed components. (They need not be equal in magnitude, but a pure left-handed electron does not satisfy the Dirac equation and so does not exist as a free particle). Then the weak nuclear force couples only to the left-handed component of the electron, while the EM force interacts with both.
 

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