  We discuss lepton number violation in three units. From an effective field
theory point of view, $\Delta L=3$ processes can only arise from dimension 9 or
higher operators. These operators also violate baryon number, hence many of
them will induce proton decay. Given the high dimensionality of these
operators, in order to have a proton half-life in the observable range, the new
physics associated to $\Delta L=3$ processes should be at a scale as low as 1
TeV. This opens up the possibility of searching for such processes not only in
proton decay experiments but also at the LHC. In this work we analyze the
relevant $d=9,11,13$ operators which violate lepton number in three units. We
then construct one simple concrete model with interesting low- and high-energy
phenomenology.

High Energy Physics - Phenomenology;High Energy Physics - Experiment