Role of polarizations and spin-spin correlations of $W's$ in $e^-e^+ \to W^-W^+$ at $\sqrt{s} = 250$ GeV to probe anomalous $W^-W^+Z/\gamma$ couplings

TL;DR

This study investigates how polarization and spin-spin correlations of W bosons in electron-positron collisions can be used to detect anomalous couplings, employing machine learning techniques to improve sensitivity at the ILC.

Contribution

The paper introduces a novel approach using polarization and spin correlations combined with neural networks to constrain anomalous W couplings at the ILC.

Findings

Polarization and spin correlations improve sensitivity to anomalous couplings.

ANN and BDT effectively distinguish jet types for asymmetry measurements.

Stronger limits on anomalous couplings compared to previous studies.

Abstract

We study anomalous $W^-W^+Z/\gamma$ couplings due to dimension-$6$ operators in the production process $e^-e^+ \to W^-W^+$ followed by semi-leptonic decay using polarizations and spin-spin correlations of $W$ bosons. The construction of some of the polarization and spin-spin correlation asymmetries required one to distinguish between two decay quarks coming from $W^+$ decay. We developed an artificial neural network (ANN) and a boosted decision tree (BDT) to distinguish down-type jets from up-type jets and used them to put constraint on anomalous couplings at International Linear Collider (ILC) running at $\sqrt{s} = 250$ GeV with integrated luminosities of $\mathcal{L} \in \{100 \ \text{fb}^{-1}, \ 250 \ \text{fb}^{-1}, \ 1000 \ \text{fb}^{-1}, \ 3000 \ \text{fb}^{-1}\}$. We find that the use of polarization and spin correlation observables, on top of the cross-sections, significantly improves the limits on anomalous coupling compared to the earlier studies.