What is the difference between left and right Weyl spinors in particle physics?

[paweld]

What is the difference between left and right Weyl spinors?
(probably they transform differently under boosts or rotations).
Thanks for answer.

 

[matonski]

They transform the same under rotations. Differently under boosts.

 

[paweld]

Thanks.
So why they are called right and left??

 

[matonski]

The particles associated with the right handed Weyl spinors are right handed. That means that their spin is pointed in the same direction as their momentum. The particles associated with the left handed spinors have their spin pointed opposite to their momentum.

 

[paweld]

I understand your point in case of masless particle (in this case right
and left spinors are decoupled). Do you have any idea if this interpretation
works for electrons (with mass).

 

[matonski]

For particles with mass, there's a distinction between helicity and chirality. The interpretation I said above is an interpretation of helicity. I don't really know of a good physical interpretation of chirality in this case.

 

[javierR]

For massive particles, the chirality depends on the reference frame; so boosting can take one between left and right chiralities. For massless particles, the handedness cannot change with boosting to different frames. Otherwise, the handedness of chirality for massive particles has the same meaning as the handedness of the helicity for massless particles. An electron with spin component +1/2 relative to the z-axis can look like it has spin component -1/2 if you go to a frame that's moving in the z-direction relative to the electron. (The presence of the mass term in the Dirac equation "spoils" the reducibility of the equation into left and right pieces, which would otherwise be called Weyl equations).