Constraining the top-Higgs sector of the Standard Model Effective Field Theory

TL;DR

This paper analyzes the constraints on top-Higgs interactions within the Standard Model Effective Field Theory, emphasizing the importance of indirect probes and operator mixing in setting bounds on new physics effects.

Contribution

It provides a comprehensive analysis of top-Higgs couplings, including renormalization group evolution, and highlights the significance of indirect constraints and operator correlations.

Findings

Indirect probes are often more constraining than direct collider measurements.

Operator mixing plays a crucial role in constraining top-Higgs couplings.

Minimal flavor violation does not significantly alter the bounds.

Abstract

Working in the framework of the Standard Model Effective Field Theory, we study chirality-flipping couplings of the top quark to Higgs and gauge bosons. We discuss in detail the renormalization group evolution to lower energies and investigate direct and indirect contributions to high- and low-energy CP-conserving and CP-violating observables. Our analysis includes constraints from collider observables, precision electroweak tests, flavor physics, and electric dipole moments. We find that indirect probes are competitive or dominant for both CP-even and CP-odd observables, even after accounting for uncertainties associated with hadronic and nuclear matrix elements, illustrating the importance of including operator mixing in constraining the Standard Model Effective Field Theory. We also study scenarios where multiple anomalous top couplings are generated at the high scale, showing that while the bounds on individual couplings relax, strong correlations among couplings survive. Finally, we find that enforcing minimal flavor violation does not significantly affect the bounds on the top couplings.