NNLOPS accurate predictions for $W^+W^-$ production

We present novel predictions for the production of W$^{+}$W$^{−}$ pairs in hadron collisions that are next-to-next-to-leading order accurate and consistently matched to a parton shower (NNLOPS). All diagrams that lead to the process $ pp\to {e}^{-}{\overline{\nu}}_e{\mu}^{+}{\nu}_{\mu }+X $ are taken into account, thereby including spin correlations and off-shell effects. For the first time full NNLOPS accuracy is achieved for a 2 → 4 process. We find good agreement, at the 1σ level, with the W$^{+}$W$^{−}$ rates measured by ATLAS and CMS. The importance of NNLOPS predictions is evident from differential distributions sensitive to soft-gluon effects and from the large impact (10% and more) of including next-to-next-to-leading order corrections on top of MiNLO. We define a charge asymmetry for the W bosons and the leptons in W$^{+}$W$^{−}$ production at the LHC, which is sensitive to the W polarizations and hence can be used as a probe of new physics.