Monday, October 20, 2014

quantum chromodynamics - Do gluons have properties other than color charge that distinguish them from each other?


Gluons in quantum chromodynamics (QCD) come in eight color charge varieties. But, it has never been clear to me if they differ from each other in other respects the way that, for example, photons do. Obviously, they also have a direction and location associated with them (subject to the uncertainty principle) and presumably, as massless bosons, always travel as the speed of light.


Do they have different frequencies or differing amounts of energy? Do they have different helicity? Do they have polarizations or chirality that is distinct from color charge? Are there other possible properties that I've overlooked?




Answer



Gluons are essentially a more complicated version of photons; their colours are just a multidimensional analogue of electric charge (which photons don't even have, because electromagnetism isn't self-interacting). In particular, gluons are massless spin-$1$ bosons. This gives the same polarisation, chirality and helicity details as photons, and an arbitrary four-momentum (satisfying $k_\mu k^\mu=0$ if the gluon is real).


No comments:

Post a Comment

classical mechanics - Moment of a force about a given axis (Torque) - Scalar or vectorial?

I am studying Statics and saw that: The moment of a force about a given axis (or Torque) is defined by the equation: $M_X = (\vec r \times \...