Study of anomalous W^-W^+γ /Z couplings using polarizations and spin correlations in e^-e^+→ W^-W^+ with polarized beams

We investigate the anomalous W^-W^+γ /Z couplings in e^-e^+→ W^-W^+ followed by semileptonic decay using a complete set of polarization and spin correlation observables of W boson with the longitudinally polarized beam. We consider a complete set of dimension-six operators affecting W^-W^+γ /Z vertex, which are SU(2)× U(1) gauge invariant. Some of the polarization and spin correlation asymmetries average out if the daughter of W^+ is not tagged and to overcome this we developed an artificial neural network and boosted decision trees to distinguish down-type jets from up-type jets. We obtain bounds on the anomalous couplings using MCMC analysis at √(s) = 250 GeV with integrated luminosities of ℒ∈{100 fb^-1, 250 fb^-1, 1000 fb^-1, 3000 fb^-1} and different sets of systematic errors. We find that using spin-related observables along with cross section in the presence of initial beam polarization significantly improves the bounds on anomalous couplings compared to previous studies.