Haotian Cao,SBU& Northwestern U, [HET Seminar] Single-spin measurements and heavy new physics in the $e^+e^- \to t\bar{t}$ process at an FCC-ee

Thursday 29 Jan 2026, 11:00 → 13:00 US/Eastern

Small Seminar Room

We investigate the sensitivity of a future FCC-ee collider to heavy new physics in$e^+e^- \to t\bar{t}$ within the Standard Model Effective Field Theory (SMEFT) framework. Focusing on the full set of spin observables encoded in the spin-density matrix, we show that single-spin measurements provide competitive and sometimes stronger probes of dimension-six Wilson coefficients than traditional unpolarized rates and spin-correlation observables. In particular, single-spin observables access complementary combinations of SMEFT parameters and play a crucial role in lifting flat directions in the parameter space. A numerical study at $\sqrt{s}=365$ GeV demonstrates that FCC-ee precision data can constrain new physics at scales well above the collider energy.

 

https://bnl.zoomgov.com/j/16010362754?pwd=Z1l1SS9JUDlyR1hSUHNyaDV1dTZHUT09 

2026.1.29.BNL.pdf