  We investigate the potential of $\gamma\gamma$ collisions to probe scalar
unparticle couplings via top-antitop quark pair production. We find 95%
confidence level limits on the unparticle couplings with an integrated
luminosity of $500 fb^{-1}$ and $\sqrt{s}=1$ TeV energy. We investigate the
effect of top quark spin polarization on the unparticle couplings. It is shown
that spin polarization of the top quark leads to a significant improvement in
the sensitivity limits.

High Energy Physics - Phenomenology