2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195973The azimuthal correlation between the planes formed by the vectors $(\vec{p}_\ell,\vec{p}_{X_b})$ and $(\vec{p}_\ell,\vec{P}_t)$ in the semileptonic rest frame decay of a polarized top quark $t(\uparrow) \to X_b + l^+ + ν_\ell$ belongs to a class of polarization observables involving the top quark which vanish at the Born term level in the standard model. We determine the next--to--leading order QCD corrections to the afore-mentioned azimuthal correlation and compare the result to the corresponding contribution of a non--standard--model right--chiral quark current.latex, 12 pages with 2 figures in the text, typos removed,comment and references added, replaced with published versionHigh Energy Physics - PhenomenologyAzimuthal correlation between the $(\vec{p}_l,\vec{p}_{X_b})$ and $(\vec{p}_l,\vec{P}_t)$ planes in the semileptonic rest frame decay of a polarized top quark: An $O(α_s)$ effecttext