NLO QCD Predictions for off-shell $t \bar t$ and $t \bar t H$ Production and Decay at a Linear Collider

TL;DR

This paper provides high-precision NLO QCD predictions for off-shell top-antitop and top-antitop-Higgs production and decay at future linear colliders, crucial for accurate top-quark Yukawa coupling measurements.

Contribution

It introduces automated NLO QCD calculations for off-shell top processes at linear colliders, including non-resonant and interference effects, enhancing top-quark phenomenology precision.

Findings

Predictions include non-resonant and interference effects at NLO.

Simulations use WHIZARD with OpenLoops for automation.

Results enable precise top-quark Yukawa coupling determination.

Abstract

We present predictions for $t \bar t$ and $t \bar t H$ production and decay at future lepton colliders including non-resonant and interference contributions up to next-to-leading order (NLO) in perturbative QCD. The obtained precision predictions are necessary for a future precise determination of the top-quark Yukawa coupling, and allow for top-quark phenomenology in the continuum at an unprecedented level of accuracy. Simulations are performed with the automated NLO Monte-Carlo framework WHIZARD interfaced to the OpenLoops matrix element generator.