What are mesons made of?

Mesons are subatomic particles that are composed of a quark-antiquark pair. This configuration means that one of the quarks carries a positive charge, while the corresponding antiquark carries a negative charge, resulting in a net integer charge for the meson itself. The interaction between the quark and the antiquark within a meson is held together by the strong force, which is mediated by gluons.

In contrast, other options do not accurately describe the structure of mesons. For example, particles made of three quarks are categorized as baryons rather than mesons. Lepton pairs, like electrons or neutrinos, do not have any correspondence to mesons. Lastly, while protons and neutrons are comprised of three quarks each (thus being baryons as well), they do not form mesons. Understanding these distinctions clarifies why mesons are specifically identified as being made up of quark-antiquark pairs.