Probing large extra dimensions with spin configuration of top quark pair production at the JLC

Abstract

We explore signatures of large extra dimensions with a polarized electron/positrn beam at the Joint Linear Collider (JLC). We point out that spin informations can be useful to study indirect signals for large extra dimensions due to spin-2 nature of Kaluza-Klein gravitons. The spin configurations of the top quark pair production at $e^{+}{e}^{-}$ and $\gamma \gamma$ collisions provide an unique testing ground to search for effects of the large extra dimensions. Especially we show the forward-backward asymmetry is a good probe at $e^{+}{e}^{-}\to t\bar{t}$ process and we can define a new asymmetry observable effective for $\gamma \gamma \to t\bar{t}$ process.

14 pages, 4 figures. To be published in the proceedings of the theory meeting on physics at Linear Colliders, 15 - 17 March 2001, KEK, Japan