Effect of top quark spin on the unparticle couplings in \gamma\gamma \to t\bar{t}

Abstract

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 $500f{b}^{-1}$ 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.

Comments: 6 figures and 4 tables, limits for d_U=1.7 and 1.9 have been added, published version