Exploring the Stabilty of Baryons: Protons and Neutrons as the Exceptions

Stability of Baryons

Baryons are a class of subatomic particles comprised of three quarks. Among the myriad particles in the universe, protons and neutrons stand out as the two stable baryons, found primarily within atom nuclei. However, why do only these two baryons remain stable, while others do not?

Baryon Definition

Baryons are defined as particles composed of three quarks. Specifically, protons, composed of uud quarks, and neutrons, composed of udd quarks, are the lightest baryons and the most stable due to their lower mass and the forces operating within them.

Decay of Heavier Baryons

Other baryons such as hyperons (which contain strange quarks) or heavier baryons like delta baryons are unstable. These particles tend to decay into protons, neutrons, or other particles via weak interactions. Common examples include:

The Lambda baryon (Λ) decays into a proton and a pion. Sigma baryons (Σ) undergo a variety of decay processes, often involving pions.

Mass and Energy Considerations

The stability of a particle is tightly coupled with its mass and the available decay channels. Baryons that are heavier than their decay products can decay into lighter, more stable particles due to the excess mass they possess. The mass of these heavier baryons prevents them from achieving a stable configuration.

Baryon Number Conservation

In any decay process, the baryon number must be conserved. Protons and neutrons are the lightest baryons and thus provide the only possible stable configurations within the context of ordinary matter. Any heavier baryons will decay into these states.

Stable Quarks and Their Combinations

Among the six known quarks, only the up (u) and down (d) quarks are inherently stable. The remaining four quarks (strange, charm, bottom, and top) are inherently unstable. The eletrostatic charge requirement for stable combinations imposes constraints, leading to the most common stable combinations of quarks as protons (uud, charge 1) and neutrons (udd, charge 0). Any combination with a non-whole number charge, such as uuu, ddd, or uddd, is inherently unstable and prone to decay.

Summary: The only stable baryons in nature are protons and neutrons. Their stability is a result of their mass, the available decay channels, and the conservation of baryon number. All other baryons are inherently unstable or decay into protons and neutrons.

Keywords: baryons, protons, neutrons