1. What are Hadrons?
Hadrons are composite subatomic particles that are made up of quarks and are held together by the strong nuclear force. This force is mediated by particles called gluons.
Hadrons are not elementary particles; they have internal structure and play a crucial role in nuclear and particle physics.
✔ All particles that participate in strong interaction are hadrons.
2. Classification of Hadrons
(a) Baryons
Baryons are hadrons composed of three quarks (qqq). They have baryon number = +1.
(b) Mesons
Mesons are hadrons composed of a quark–antiquark pair (q q̄). They have baryon number = 0.
| Type | Quark Structure | Baryon Number | Spin |
|---|---|---|---|
| Baryons | qqq | +1 | Half-integer |
| Mesons | q q̄ | 0 | Integer |
3. Examples of Hadrons
Baryons
- Proton (uud)
- Neutron (udd)
- Lambda (Λ)
- Sigma (Σ)
Mesons
- Pion (π⁺, π⁰, π⁻)
- Kaon (K)
- Eta (η)
4. Properties of Hadrons
| Property | Description |
|---|---|
| Mass | Relatively large compared to leptons |
| Charge | Can be positive, negative or neutral |
| Spin | Half-integer (baryons) or integer (mesons) |
| Interaction | Strong, electromagnetic, weak, gravitational |
| Stability | Most hadrons are unstable except proton |
5. Why Are Hadrons Important?
Hadrons form the building blocks of atomic nuclei. Protons and neutrons, which are baryons, make up all ordinary matter. Studying hadrons helps us understand:
- Strong nuclear force
- Quark confinement
- Particle interactions at high energy
6. Key Points to Remember
🔹 All baryons and mesons are hadrons
🔹 All hadrons are made of quarks
🔹 All hadrons participate in strong interaction
🔹 Hadrons are NOT elementary particles
🔹 All hadrons are made of quarks
🔹 All hadrons participate in strong interaction
🔹 Hadrons are NOT elementary particles