An operator that changes this quantity by two is included in theories that allow for neutron–antineutron oscillation. This quantity is the topological charge of skyrmions, which are used to model nuclei. This quantity is the alphabetically [emphasize] first of the two quantities that change in a transition across a sphaleron (“s’FAY-lur-on”) barrier. In GUTs (“guts”) based on the gauge group SU(5) (“S-U-5”), this quantity minus a different quantity is (10[1])conserved, but this quantity itself is not conserved. The violation of C and CP symmetry, the existence of out-of-equilibrium processes, and non-conservation of this quantity are the Sakharov conditions on the early universe. One third times the difference between the number of quarks and the number of antiquarks equals (10[1])this quantity, which is denoted with a capital B. For 10 points, name this quantity that equals one for particles composed of three quarks and equals zero for mesons (“meh-zahns”) and leptons. ■END■