Different Interactions
Both strong and weak interactions cause particle decays.
Before explaining
some differences between these interactions,
it is necessary to redefine a few
key terms.
-
Electromagnetic Charge:
- Particles with
electromagnetic charge
attract particles with opposite electric charge,
and repel particles with similar charges. The
electromagnetic interaction has been unified with the weak interaction into
the Electroweak interaction.
-
Color Charge:
- Just as some particles can be electromagnetically charged,
other particles
have a different kind of charge called
color charge. The strong interaction
causes the attraction between color charged particles.
-
Flavor:
- A particle's type is referred to as its "flavor."
If a particle decays from one type to another it "changes flavor."
When a down quark decays into an up quark it would be incorrect to say
that the down quark suddenly ceased to be; instead, the down quark
changed flavor.
The force carrier for the strong interaction is the electrically
neutral, color-charged gluon.
The force carriers for the weak interaction are the
W+
(electrically positive),
W- (electrically negative),
and the Z (no electric charge).
None of the weak force-carrier particles are color charged.
Typically, the weak force-carrier particles
(W±) mediate decays in which
particles change electric charge. This usually happens whenever a particle
changes flavor.
The strong force-carrier particle (the
gluon) mediates decays involving a color change.
Strong interactions, being stronger, happen faster than weak interactions.
Look at more information and pictures which use the example of
neutron beta decay to explain the weak interaction.