  The Twin Higgs model provides a natural theory for the electroweak symmetry
breaking without the need of new particles carrying the standard model gauge
charges below a few TeV. In the low energy theory, the only probe comes from
the mixing of the Higgs fields in the standard model and twin sectors. However,
an ultraviolet completion is required below ~ 10 TeV to remove residual
logarithmic divergences. In non-supersymmetric completions, new exotic fermions
charged under both the standard model and twin gauge symmetries have to be
present to accompany the top quark, thus providing a high energy probe of the
model. Some of them carry standard model color, and may therefore be copiously
produced at current or future hadron colliders. Once produced, these exotic
quarks can decay into a top together with twin sector particles. If the twin
sector particles escape the detection, we have the irreducible stop-like
signals. On the other hand, some twin sector particles may decay back into the
standard model particles with long lifetimes, giving spectacular displaced
vertex signals in combination with the prompt top quarks. This happens in the
Fraternal Twin Higgs scenario with typical parameters, and sometimes is even
necessary for cosmological reasons. We study the potential displaced vertex
signals from the decays of the twin bottomonia, twin glueballs, and twin
leptons in the Fraternal Twin Higgs scenario. Depending on the details of the
twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and
beyond 10 TeV at a future 100 TeV collider, providing a strong test of this
class of ultraviolet completions.
