  Massive Z'-gauge bosons act as excellent harbingers for string
compactifications with a low string scale. In D-brane models they are
associated to U(1) gauge symmetries that are either anomalous in four
dimensions or exhibit a hidden higher dimensional anomaly. We discuss the
possible signals of massive Z'-gauge bosons at hadron collider machines
(Tevatron, LHC) in a minimal D-brane model consisting out of four stacks of
D-branes. In this construction, there are two massive gauge bosons, which can
be naturally associated with baryon number B and B-L (L being lepton number).
Here baryon number is always anomalous in four dimensions, whereas the presence
of a four-dimensional B-L anomaly depends on the U(1)-charges of the right
handed neutrinos. In case B-L is anomaly free, a mass hierarchy between the two
associated Z'-gauge bosons can be explained. In our phenomenological discussion
about the possible discovery of massive Z'-gauge bosons, we take as a benchmark
scenario the dijet plus W signal, recently observed by the CDF Collaboration at
Tevatron. It reveals an excess in the dijet mass range 150 GeV/c^2, 4.1\sigma
beyond SM expectations. We show that in the context of low-mass string theory
this excess can be associated with the production and decay of a leptophobic
Z', a singlet partner of SU(3) gluons coupled primarily to baryon number. Even
if the CDF signal disappears, as indicated by the more recent D0 results, our
analysis can still serve as the basis for future experimental search for
massive Z'-gauge bosons in low string scale models. We provide the relevant
cross sections for the production of Z'-gauge bosons in the TeV region, leading
to predictions that are within reach of the present or the next LHC run.
