Feasibility study of the forward-backward asymmetry of the e+e- -> t tbar process in all-hadronic decay modes at sqrt(s) = 500 GeV with the ILD detector

TL;DR

This study assesses the measurement precision of the forward-backward asymmetry in top quark pair production at 500 GeV using the ILD detector, demonstrating high statistical accuracy in all-hadronic decay modes.

Contribution

It presents a detailed feasibility analysis of measuring the forward-backward asymmetry in all-hadronic top pair decays at the ILC, utilizing vertex charge techniques for event reconstruction.

Findings

Measured asymmetry $A^t_{FB} = 0.334 \, \pm \, 0.0079$ with 500 fb$^{-1}$

Achieved approximately 2% statistical accuracy in the 6-jet mode

Demonstrated effective charge identification and asymmetry extraction

Abstract

We have studied the measurement accuracy of the forward-backward asymmetry of the $e^+e^- \rightarrow t\bar{t}$ process in the 6-jet mode at $\sqrt{s} = 500$ GeV with the ILD detector. In the analysis the vertex charges of b-jets were used to distinguish t from $\bar{t}$ in each event. The distribution of the cosine of the reconstructed polar angle of so identified t or $\bar{t}$ showed a clear forward-backward asymmetry. After the correction for charge misidentification the forward-backward asymmetry was determined to be $A^t_{FB} = 0.334 \pm 0.0079$ for 500 fb$^{-1}$ with the beam polarization combination of $P(e^+, e^-) = (+30\%, -80\%)$, demonstrating a very good statistical accuracy ($\sim 2\%$) even in the 6-jet mode.