Top-spin analysis of new scalar and tensor interactions in e⁺e^- collisions with beam polarization

Abstract

We utilize top polarization in the process e⁺ e^-→tt̅ at the International Linear Collider (ILC) with transverse beam polarization to probe interactions of the scalar and tensor type beyond the standard model and to disentangle their individual contributions. Ninety percent confidence level limits on the interactions with realistic integrated luminosity are presented and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times 10^-3  TeV^-2 for real and imaginary parts of both scalar and tensor couplings at √s=500 and 800 GeV with an integrated luminosity of 500  fb^-1 and completely polarized beams are shown to be possible. A powerful model-independent framework for inclusive measurements is employed to describe the spin-momentum correlations, and their C, P, and T properties are presented in a technical appendix.