First simultaneous measurement of single and pair production of top quarks in association with a Z boson at the LHC

TL;DR

This paper reports the first simultaneous measurement of single and pair top quark production with a Z boson at the LHC, providing more robust insights into top quark interactions and potential new physics.

Contribution

It introduces a novel simultaneous measurement approach for multiple top quark production processes, reducing dependence on signal modeling and enhancing sensitivity to new physics.

Findings

First measurement of combined top quark production with Z boson at the LHC

Use of multiclass neural network for signal-background separation

Improved constraints on deviations from the Standard Model

Abstract

The first simultaneous measurement of single and pair production of top quarks in association with a Z boson ($t$Zq, $t$WZ and $t\bar{t}$Z) is presented, including both inclusive and differential cross sections. A multiclass neural network is used to separate the signal and the backgrounds. Compared to previous studies, the simultaneous measurement is less dependent on the signal modeling assumptions and improves the sensitivity to new physics scenarios, as it enables to constrain possible deviations from the standard model across different processes.