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

1. Jul 24, 2004

### Rhizomorph

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.

2. Jul 24, 2004

### marlon

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.

3. Jul 24, 2004

### Rhizomorph

"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?

4. Jul 26, 2004

### zefram_c

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.