Why do Quarks Have Fractional Charges?

摘要

The quark model has a long history. The notion of quarks was introduced on the basis of unitary symmetry SU(3) for hadrons. This tradition lasts in the modern books on particle physics. We want to mention that quark's fractional charge follows only from the compound nature of hadrons without any references to some symmetry. The constituent quarks must be fermions, and because charge is additive physical quantity, the sum of quarks' charge must be equal to the total charge of hadron. Normalization is chosen on charges of proton and neutron. The obtained linear system of equations is simply solvable and the solutions give the true values for quarks' charge. Therefore, this approach seems to be much more simple and do not require consideration of some methods of group theory. We consider this approach more simple and reasonable for student understanding.