WEAK
There is one more interaction that needs explaining: Weak.
Weak interactions are the only processes in which a quark can
change to another quark, or a lepton to another lepton.
When a lepton or quark changes type it is called changing
flavor.
Weak interactions are responsible for the fact that all the more massive
quarks and leptons decay to produce lighter quarks and leptons. When a
particle decays, it disappears and in its place two or more particles
appear. The sum of the masses of the produced particles is always less
than the mass of the original particle. This is why stable matter around
us contains only electrons and the lightest two quarks (up and down.)
The carrier particles of the weak interactions are the W+, W- and the Z
bosons . The W's are electrically
charged and the Z is neutral.
It was research in radioactivity
that first revealed the existence of the weak interaction.
Electroweak
Force Carrier Chart
Interactions Chart