Probing top-Z dipole moments at the LHC and ILC

TL;DR

This paper explores the potential of the LHC and ILC to measure the weak electric and magnetic dipole moments of top quark-Z boson interactions, which are sensitive indicators of new physics beyond the Standard Model.

Contribution

It provides a detailed next-to-leading order QCD analysis of top-Z dipole moments at collider experiments, including full decay chains and uncertainty assessments.

Findings

LHC can soon probe weak dipole moments of top quarks.

Complementary constraints from LHC and ILC improve sensitivity.

The analysis includes full decay chains and theoretical uncertainties.

Abstract

We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boson interactions and complement indirect constraints from electroweak precision data. Our computation is accurate to next-to-leading order in QCD, we include the full decay chain of top quarks and the Z boson, and account for theoretical uncertainties in our constraints. We find that LHC experiments will soon be able to probe weak dipole moments for the first time.