1
$\begingroup$

The question is in the title. I know that, e.g., W bosons change the flavour in electroweak processes. What do gluons do?

$\endgroup$
  • 2
    $\begingroup$ Does it clarify or confuse if I ask you what photons and $Z^0$ do? $\endgroup$ – dmckee Aug 21 at 22:38
  • $\begingroup$ I wanted to add these questions but I didn't due to comments that I shall create a new question! :) Hence, I'm interested in them as well! $\endgroup$ – Ben Aug 21 at 23:19
  • 2
    $\begingroup$ Ben, I believe the point @dmckee is making is that the W boson $W^0$ (which mixes with the $B$ to form the $Z^0$ after the HIggs condensates break the symmetry) in the unbroken weak interaction does not change the flavor when absorbed or emitted. See weak neutral currents $\endgroup$ – Alfred Centauri Aug 21 at 23:59
  • 1
    $\begingroup$ I couldn't tell is Ben though "exchanging charge" was a fundamental of gauge bosons or not, so I thought I'd throw out some examples that didn't have that property to make sure he had a broad enough picture. $\endgroup$ – dmckee Aug 22 at 0:03
  • 2
    $\begingroup$ @ben Spontaneous symmetry breaking is a fun world. The degrees of freedom that we see at human energy scales are not the right degrees of freedom at to use in describing things above the electroweak scale. What "particles" make up the theory depends on the energy scale at which you ask the question. $\endgroup$ – dmckee Aug 22 at 0:36
3
$\begingroup$

Emitting or absorbing a gluon changes the color of a quark. This is because gluons themselves have color.

However, as @dmckee points out, not all gauge bosons change some property (other than energy and momentum) of the particle emitting or absorbing them. For example, photons are not charged, so emitting or absorbing a photon does not change the charge of an electron.

The fact that gluons carry color while photons do not carry charge is related to the fact that the $SU(3)$ gauge symmetry group of the strong interaction is non-commutative while the $U(1)$ gauge symmetry group of the electromagnetic interaction is commutative.

$\endgroup$
  • 2
    $\begingroup$ To be sure, gluons have both color and anticolor, e.g., blue and antired. $\endgroup$ – Alfred Centauri Aug 21 at 23:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.