What are pretons?

It seems like there may be a typo in your question. It is possible that you meant to ask about "protons" instead of "pretons."

Protons are subatomic particles that are found in the nucleus of an atom. They have a positive electric charge and are important for determining the atomic number of an element. Protons are made up of smaller particles called quarks, specifically two up quarks and one down quark.