Phenomenology of neutron-antineutron conversion

We consider the possibility of neutron-antineutron (n-n) conversion, in which the change of a neutron into an antineutron is mediated by an external source, as can occur in a scattering process. We develop the connections between n-n conversion and n-n oscillation, in which a neutron spontaneously transforms into an antineutron, noting that if n-n oscillation occurs in a theory with baryon number minus lepton number (B-L) violation, then n-n conversion can occur also. We show how an experimental limit on n-n conversion could connect concretely to a limit on n-n oscillation, and vice versa, using effective field theory techniques and baryon matrix elements computed in the MIT bag model.