  We propose a low energy extension of the Standard Model consisting of an
additional gauged $U(1)_{B-L}$ plus three right-handed neutrinos. The lightest
right-handed neutrinos have TeV scale masses and may be produced at colliders
via their couplings to the $Z_{B-L}$ gauge boson whose mass and gauge coupling
is constrained by the out-of-equilibrium condition leading to upper bounds on
the right-handed neutrino and $Z_{B-L}$ production cross-sections at colliders.
We propose a brane-world scenario which motivates such TeV mass right-handed
neutrinos. Our analysis opens up the possibility that the mechanism responsible
for neutrino mass is testable at colliders such as the LHC or VLHC.
