$W^{\pm }Z$ production at the LHC: fiducial cross sections and distributions in NNLO QCD

Abstract

We report on the first fully differential calculation for $W^{\pm }Z$ production in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. Leptonic decays of the $W$ and $Z$ bosons are consistently taken into account, i.e. we include all resonant and non-resonant diagrams that contribute to the process $pp\to {\ell }^{{}^{\prime }\pm }{\nu }_{{\ell }^{{}^{\prime }}}{\ell }^{+}{\ell }^{-}+X$ both in the same-flavour (${\ell }^{\prime }=\ell$) and the different-flavour (${\ell }^{\prime }\ne \ell$) channel. Fiducial cross sections and distributions are presented in the presence of standard selection cuts applied in the experimental $W^{\pm }Z$ analyses by ATLAS and CMS at centre-of-mass energies of 8 and 13\,TeV. As previously shown for the inclusive cross section, NNLO corrections increase the NLO result by about $10\%$, thereby leading to an improved agreement with experimental data. The importance of NNLO accurate predictions is also shown in the case of new-physics scenarios, where, especially in high-$p_T$ categories, their impact can reach $\mathcal{O}(20\%)$. The availability of differential NNLO predictions will play a crucial role in the rich physics programme that is based on precision studies of $W^{\pm }Z$ signatures at the LHC.

Comments: 38 pages, 18 figures, 8 tables