valencequarks

Valence quarks are the quarks that are present in a hadron (such as a proton or neutron) and contribute to its quantum numbers, including its spin and isospin. They are the quarks that are not created or annihilated in the strong interaction processes that occur within the hadron. The number of valence quarks in a hadron is determined by its flavor content. For example, a proton has two up quarks and one down quark as valence quarks, while a neutron has two down quarks and one up quark as valence quarks. The remaining quarks in a hadron are called sea quarks and are created and annihilated in the strong interaction processes. The concept of valence quarks is fundamental to the quark model of hadrons, which was proposed by Murray Gell-Mann and George Zweig in the early 1960s. The quark model has been confirmed by numerous experiments and is now widely accepted as the correct description of the strong interaction.