The fundamental particle which are responsible for keeping nucleons together is

Answer

**Step-by-Step Solution:**

1. **Understanding Nucleons**: Nucleons are the particles found in the nucleus of an atom, which include protons and neutrons.

2. **Identifying the Forces in the Nucleus**: The nucleons are held together in the nucleus by a force known as the strong nuclear force.

3. **Role of Fundamental Particles**: The fundamental particles that mediate the strong nuclear force between nucleons are called mesons.

4. **Types of Mesons**: Among the mesons, the most notable is the pion (π meson), which comes in three varieties: π+, π-, and π0. The neutral pion (π0) is particularly important as it is suggested to be responsible for the binding forces between nucleons.

5. **Conclusion**: Therefore, the fundamental particles responsible for keeping nucleons together in the nucleus are mesons.

**Final Answer**: Mesons are the fundamental particles responsible for keeping nucleons together.

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