Probing anomalous $t\bar t Z$ interactions with rare meson decays

TL;DR

This paper investigates how rare meson decays and electroweak measurements can constrain anomalous top-Z interactions, which are weakly limited by direct searches, using an effective field theory framework.

Contribution

It introduces a comprehensive analysis of dimension-six operators affecting top-Z couplings and derives constraints from meson decays and electroweak data.

Findings

Rare meson decays impose strong bounds on anomalous top-Z couplings.

Electroweak precision observables further tighten these constraints.

Single-top production data also contribute to constraining the interactions.

Abstract

Anomalous couplings of the $Z$ boson to top quarks are only marginally constrained by direct searches and are still sensitive to new particle dynamics at the TeV scale. Employing an effective field theory approach we consider the dimension-six operators which generate deviations from the standard-model vector and axial-vector interactions. We show that rare $B$ and $K$ meson decays together with electroweak precision observables provide strong constraints on these couplings. We also consider constraints from t-channel single-top production.