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

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.

Comments: 17 pages, 26 figures