Neutron-antineutron conversion to search for B-L violation

The observation of the violation of baryon number minus lepton number (B-L) would reveal the existence of physics beyond the Standard Model, and it would prove that fundamental Majorana dynamics exists. We propose searching for B-L violation through $n-\bar{n}$ conversion, in which the $|\Delta B|=2$ process is mediated by an external source. We construct the leading-mass-dimension, quark-level operators for $n-\bar{n}$ conversion since they differ from those for $n-\bar{n}$ oscillation, and we evaluate the sensitivity of possible scattering experiments to B-L violating parameters. Finally we show, under particular assumptions, how a limit on $n$-${\bar n}$ conversion can be interpreted as a limit on the neutron's Majorana mass.