  We investigate B3 mSUGRA models, where the lightest scalar tau, stau_1, is
the LSP. B3 models allow for lepton number and R-parity violation; the LSP can
thus decay. We assume one non-zero B3 coupling lambda'_ijk at M_GUT, which
generates further B3 couplings at M_Z. We study the RGEs and give numerical
examples. The new couplings lead to additional stau_1 decays, providing
distinct collider signatures. We classify the stau_1 decays and describe their
dependence on the mSUGRA parameters. We exploit our results for single slepton
production at the LHC. As an explicit numerical example, we investigate single
smuon production, focussing on like-sign dimuons in the final state. Also
considered are final states with three or four muons.
