Measurement of ${W}^{±}$ -boson and Z-boson production cross-sections in pp collisions at $\sqrt{s}=2.76$ TeV with the ATLAS detector

The production cross-sections for ${W}^{±}$ and Z bosons are measured using ATLAS data corresponding to an integrated luminosity of 4.0 pb ${}^{-1}$ collected at a centre-of-mass energy $\sqrt{s}=2.76$ TeV. The decay channels $W\to \ell \nu $ and $Z\to \ell \ell $ are used, where $\ell $ can be an electron or a muon. The cross-sections are presented for a fiducial region defined by the detector acceptance and are also extrapolated to the full phase space for the total inclusive production cross-section. The combined (average) total inclusive cross-sections for the electron and muon channels are: $\begin{array}{cc}{\sigma }_{{W}^{+}\to \ell \nu }^{\text{tot}}=& 2312±26\phantom{\rule{4pt}{0ex}}\left(\text{stat.}\right)\\ & ±27\phantom{\rule{4pt}{0ex}}\left(\text{syst.}\right)±72\phantom{\rule{4pt}{0ex}}\left(\text{lumi.}\right)±30\phantom{\rule{4pt}{0ex}}\left(\text{extr.}\right)\phantom{\rule{3.33333pt}{0ex}}\text{pb},\\ {\sigma }_{{W}^{-}\to \ell \nu }^{\text{tot}}=& 1399±21\phantom{\rule{4pt}{0ex}}\left(\text{stat.}\right)\phantom{\rule{4pt}{0ex}}±17\phantom{\rule{4pt}{0ex}}\left(\text{syst.}\right)\\ & ±43\phantom{\rule{4pt}{0ex}}\left(\text{lumi.}\right)±21\phantom{\rule{4pt}{0ex}}\left(\text{extr.}\right)\phantom{\rule{3.33333pt}{0ex}}\text{pb},\\ {\sigma }_{Z\to \ell \ell }^{\text{tot}}=& 323.4±9.8\phantom{\rule{4pt}{0ex}}\left(\text{stat.}\right)±5.0\phantom{\rule{4pt}{0ex}}\left(\text{syst.}\right)\\ & ±10.0\phantom{\rule{4pt}{0ex}}\left(\text{lumi.}\right)±5.5\left(\text{extr.}\right)\phantom{\rule{3.33333pt}{0ex}}\text{pb}.\end{array}$ Measured ratios and asymmetries constructed using these cross-sections are also presented. These observables benefit from full or partial cancellation of many systematic uncertainties that are correlated between the different measurements.