Precise predictions for joint polarization fractions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>W</mml:mi> <mml:mi>Z</mml:mi> </mml:math> production at the LHC

We achieve for the first time NNLO <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mi>QCD</a:mi> <a:mo>+</a:mo> <a:mi>NLO</a:mi> </a:mrow> </a:math> EW accuracy for doubly polarized <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>W</c:mi> <c:mi>Z</c:mi> </c:math> inclusive production at the LHC, in the case of fully leptonic decays. Additionally, we provide estimates for missing higher-order uncertainties in QCD associated with doubly polarized differential cross sections and joint polarization fractions, obtained both with standard scale variations and with a theory-nuisance-parameter approach. The study is carried out in the fiducial setup of a recent ATLAS analysis of Run-2 data.