Nucleons comprise a subclass of baryons.
Baryon number has always appeared to have been conserved experimentally, but grand unified theories postulate interactions at very high energies that allow it not to be conserved. It is thought that non-conservation of baryon number at the high energies characteristic of the early universe may provide an explanation for the asymmetry between matter and antimatter in the universe. See proton decay . The New Penguin Dictionary of Science 3. A Dictionary of Science, Oxford University Press 4. hypercharge A Dictionary of Science, Oxford University Press 5.