There are four fundamental interactions act on the different charge carriers. These are the gravitational with mass-energy, the electromagnetic with electric charge, the weak and strong interactions with flavor and colour charges (Figure 15-04c).
The electromagnetic and weak interactions are unified at high energy into the electroweak interaction.
The strong residual interaction is experienced by hadrons (all the particles affected by the strong nuclear force) and generated by the quarks within. It is strong enough to overcome the electromagnetic repulsion between the hadrons. This is similar to the Van der Waals force between molecules (except the difference in charge carrier). Note that most of the mass of nucleons (more than 90%) arises from the energy associated with the