Protons and neutrons are bound in a nucleus by the

Protons and neutrons, collectively known as nucleons, are bound together in the atomic nucleus by the strong nuclear force [t2][t5]. This interaction is characterized as a short-range force, acting only over distances of approximately 10^-13 to 10^-15 meters [t2][t9]. It is the most powerful of the four fundamental forces, providing sufficient attraction to overcome the intense electrostatic (Coulomb) repulsion between positively charged protons [t2][t8]. While the weak interaction is also short-range, it is primarily responsible for processes like beta decay rather than nuclear binding [t2][t7]. In contrast, electromagnetic and gravitational interactions are long-range forces; however, gravity is too weak at the subatomic scale to bind nucleons, and electromagnetism would cause the nucleus to fly apart due to proton repulsion [t2][t8]. Therefore, the 'strong interaction' is the essential binding mechanism [t1][t5].

Sources

1. [1] https://www.sciencedirect.com/topics/engineering/nuclear-force