Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 97: Future colliders

T 97.1: Talk

Thursday, March 7, 2024, 16:00–16:15, Geb. 30.34: LTI

Heavy-quark precision measurements at FCC-ee — Kevin Kröninger¹, Romain Madar², Stéphane Monteil², and •Lars Röhrig^{1, 2} — ¹TU Dortmund University, Department of Physics, Dortmund — ²Université Clermont-Auvergne, Laboratoire de Physique de Clermont, Clermont-Ferrand

The FCC-ee, proposed as the successor to the Large Hadron Collider, aims at electron-positron collisions in order to achieve unprecedented precision in the electroweak sectors, producing in particular about O(10¹²) Z→ qq events. This makes it possible to measure electroweak observables related to the Z → bb coupling with a very high accurary. However, the accuracy of these measurements is expected to be limited by systematic uncertainties, primarily originating from events related to light-quark physics.

To enhance overall measurement precision, we introduce an ultra-pure b-flavour tagger. This tagger relies on exclusive b-hadron reconstruction to effectively eliminate background contributions. We evaluate its performance and discuss the remaining systematic uncertainties in the measurement of R_b = Γ(Z→ bb)/Γ(Z→ qq) and the b-quark forward-backward asymmetry A_FB^b.

These results are put in context alongside top-quark measurements at FCC-ee, allowing us to establish stringent constraints on dimension-6 operators within the SMEFT framework.

Keywords: FCC-ee; lepton collider; heavy quarks; EW precision measurements