  No process without a standard model (SM) background has been observed so far.
As a tool in the study of a class of models containing doubly charged vector
bileptons, we propose one such process that, violating lepton flavor number
conservation, has no contribution from the SM: $pp\to \mu^+\mu^+\mu^- e^-$. By
carefully isolating the parameters to keep them free, we are able to acquire a
notion of how a possible PMNS-like matrix present in the relevant charged
current parametrization could affect the observables. We find that an
interesting section of the space of parameters can be explored at the current
LHC in the specified conditions.
