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arXiv · 2511.01994

Single-spin measurements and heavy new physics in the $e^+e^- \to t\bar{t}$ process at an FCC-ee

Haotian Cao·Frank Petriello
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Abstract

We investigate the potential of single-spin components of the spin-density matrix in the $e^+ e^- \to t\bar{t}$ process at a future FCC-ee for probing heavy new physics parametrized using the SMEFT framework. We consider the full spectrum of spin observables and the complete angular decomposition of the $t\bar{t}$ production process in our study. We find that single-spin measurements generically provide stronger probes of SMEFT Wilson coefficients than measurements where the $t\bar{t}$ spins are correlated, and that single-spin observables are important for resolving flat directions that can appear in the Wilson-coefficient parameter space.

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Haotian Cao, Frank Petriello. 2025-11-03. Single-spin measurements and heavy new physics in the $e^+e^- \to t\bar{t}$ process at an FCC-ee. https://doi.org/10.1103/794y-gp3r

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