Measurement of the production cross section for a Higgs boson in association with a vector boson in the $H\to W{W}^{\ast }\to \mathrm{\ell }\nu \mathrm{\ell }\nu$ channel in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A measurement of the Higgs boson production cross sections via associated $WH$ and $ZH$ production using $H \rightarrow WW^{\ast} \rightarrow \ell\nu\ell\nu$decays,where$\ell$ stands for either an electron or a muon, is presented. Results for combined $WH$ and $ZH$ production are also presented. The analysis uses events produced in proton-proton collisions collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The data correspond to an integrated luminosity of 36.1 fb${}^{-1}$ recorded at a centre-of-mass energy of 13 TeV. The products of the $H\to W{W}^{\ast }$ branching fraction times the $WH$ and $ZH$ cross sections are measured to be $0.67_{-0.27}^{+0.31}$(stat.)${}_{-0.14}^{+0.18}$(syst.) pb and $0.54_{-0.24}^{+0.31}$(stat.)${}_{-0.07}^{+0.15}$(syst.) pb respectively, in agreement with the Standard Model predictions.