an antibaryon composed of two anti up quarks and one antidown quark
Quarks have fractional electric charge values -- either (− ​ ⁄) or (+ ​ ⁄) times the elementary charge (e), depending on flavor. Up, charm, and top quarks (collectively referred to as up-type quarks) have a charge of + ​ ⁄ e, while down, strange, and bottom quarks (down-type quarks) have − ​ ⁄ e. Antiquarks have the opposite charge to their corresponding quarks; up-type antiquarks have charges of − ​ ⁄ e and down-type antiquarks have charges of + ​ ⁄ e. Since the electric charge of a hadron is the sum of the charges of the constituent quarks, all hadrons have integer charges: the combination of three quarks (baryons), three antiquarks (antibaryons), or a quark and an antiquark (mesons) always results in integer charges. For example, the hadron constituents of atomic nuclei, neutrons and protons, have charges of 0 e and + 1 e respectively; the neutron is composed of two down quarks and one up quark, and the proton of two up quarks and one down quark.