Large Extra Dimension Effects on the Spin Configuration of the Top Quark Pair at e^+ e^- Colliders

Large extra dimension effects on the spin configuration of the top quark pair at the $e^+ e^-\to t\bar{t}$ process are studied. It is shown that the TeV scale quantum gravity effects cause significant deviations from the Standard Model predictions for the spin configuration in the off-diagonal basis: they lead to substantial cross sections of the like-spin states of the top quark pair, which vanish in the SM; they weaken the pure dominance of the processes, the Up-Down (Down-Up) spin states for the left-handed (right-handed) beam. In addition it is shown that the angular cut $-0.5<\cos\theta<0$ is very effective to determine the sign of the quantum gravity corrections.Comment: A discussion on the angular distribution is added with a tabl

Dark-Sector Photo-Magnetic Luminescence: The Case for a Room Temperature Chameleon Search

We report the results of studies showing that temperature dependent photoluminescence is the likely source of unexpected large background rates in afterglow searches for dark sector phenomena, commonly called ``chameleons''. Using this information, we examine the possibility of a room temperature chameleon afterglow search that automatically eliminates this background. Then, without this background, we discuss a modest search effort exploring the afterglow halflife range $0.1~{\rm{sec}} \leq T_{1/2} \leq 120~{\rm{sec}}$ equivalent to photon coupling constant range $8 \times10^{12} \leq \beta_{\gamma } \leq 3\times10^{14}$