Stability in the family of baryons

[DragonPetter]

Of all the baryons, why are protons the only known stable combination of quarks?
Why are neutrons more stable by more than billions of times longer than the rest of the unstable baryons? If it is just their combination of quantum numbers, then, why do those combinations work out to being stable?

 

[ofirg]

Baryon number conservation is the reason for proton stability. It is the lightest particle with non zero baryon number and thus baryon number conservation ensures its stability.
The extremley long lifetime of the neutron is due the approximate degeneracy between it and and the proton, which has to be included in its decay products (again , due to baryon number conservation). This leaves very small phase space for the decay products.

 

[DragonPetter]

Thank you for the reply. I am reading about number conservation on the hyperphysics site now.