Quark-antiquark pairs do have the potential to annihilate each other due to their opposite charges. However, in the context of the strong nuclear force, which governs the interactions between quarks, annihilation is not the dominant process.
The reason for this lies in the fundamental nature of the strong force and the way it is mediated by gluons. The strong force is carried by gluons, which themselves carry a color charge. Gluons can interact with both quarks and other gluons. When a quark and an antiquark come close together, they can exchange gluons between them, resulting in the strong force binding them together in a meson.
The strong force is unique in that it becomes stronger as the distance between quarks increases (unlike the electromagnetic force, which weakens with distance). This phenomenon, known as confinement, means that it becomes increasingly difficult to separate quarks from each other.
When a quark and an antiquark approach each other, the strong force between them becomes stronger, counteracting the electromagnetic attraction between their opposite charges. As a result, the quark and antiquark form a bound state, such as a meson, rather than annihilating each other.
In summary, the strong force and the exchange of gluons play a crucial role in preventing the annihilation of quark-antiquark pairs. Instead, they form bound states due to the confinement of quarks, resulting in the creation of mesons or other composite particles.