Final answer:
Quarks experience the strong nuclear force and have fractional electric charges, whereas leptons do not experience the strong force and have integral charges. Both interact through electromagnetic, weak nuclear, and gravitational forces and are considered fundamental particles with no substructure.
Step-by-step explanation:
Fermions, a classification of particles in particle physics, are divided into quarks and leptons. One of the key differences between these two groups is their interaction with fundamental forces. Quarks are unique because they experience the strong nuclear force, which holds them together inside hadrons like protons and neutrons. This force is mediated by gluons and is responsible for binding quarks into these larger composite particles. On the other hand, leptons, such as electrons and neutrinos, do not feel the strong nuclear force at all, making them fundamentally different from quarks.
Both quarks and leptons interact through the electromagnetic, weak nuclear, and gravitational forces. These interactions define much of their behavior in the universe. For example, charged leptons, like electrons, interact electromagnetically, while neutral leptons like neutrinos primarily interact through the weak nuclear force. Quarks experience all four fundamental forces, including the unique strong force interaction. Additionally, both types of particles are considered fundamental particles; they have no substructure and are not composed of smaller particles. This contrasts with hadrons, which are not fundamental as they are made up of quarks.
Another distinction is that quarks have fractional electric charges, while leptons have integral charges. This fundamental property difference remains a subject of inquiry in the field of particle physics. As research advances with higher-energy accelerators and insights from cosmology, scientists seek to understand these and other deep questions about the structure and behavior of fundamental particles.