  The framed standard model (FSM), constructed initially for explaining the
existence of three fermion generations and the hierarchical mass and mixing
patterns of quarks and leptons, suggests also a "hidden sector" of particles
including some dark matter candidates. It predicts in addition a new vector
boson $G$, with mass of order TeV, which mixes with the $\gamma$ and $Z$ of the
standard model yielding deviations from the standard mixing scheme, all
calculable in terms of a single unknown parameter $m_G$. Given that standard
mixing has been tested already to great accuracy by experiment, this could lead
to contradictions, but it is shown here that for the three crucial and testable
cases so far studied (i) $m_Z - m_W$, (ii) $\Gamma(Z \rightarrow \ell^ +
\ell^-)$, (iii) $\Gamma(Z \rightarrow$ hadrons), the deviations are all within
the present stringent experimental bounds provided $m_G > 1$ TeV, but should
soon be detectable if experimental accuracy improves. This comes about because
of some subtle cancellations, which might have a deeper reason that is not yet
understood. By virtue of mixing, $G$ can be produced at the LHC and appear as a
$\ell^+ \ell^-$ anomaly. If found, it will be of interest not only for its own
sake but serve also as a window on to the "hidden sector" into which it will
mostly decay, with dark matter candidates as most likely products.
