New Perspectives on $n$-$\bar n$ Oscillations

The observation of $n-{\bar n}$ oscillations would reveal that B-L symmetry is broken and thus that dynamics beyond the Standard Model exists. Notably it would establish that neutrons are their own antiparticles, making the process analogous to neutrinoless double beta decay. I will contrast the Majorana dynamics of neutrinos and neutrons, considering the transformation properties of fermions under CPT, CP, and C in the presence of B-L violation, and show that the resulting CPT phase has particular implications for the interplay of $n-{\bar n}$ oscillations with the effects of external fields and sources --- and for their observability.