Measurement of the Z to tau tau cross section with the ATLAS detector

The $Z$ to tau tau cross section has been measured using data at $\sqrt s = 7~\mathrm{TeV}$ collected with the ATLAS detector at the LHC corresponding to the integrated luminosity of $1.34 - 1.55~\mathrm{fb}^{-1}$. The analysis is performed in three different final states determined by decay modes of the tau leptons. Cross sections are measured separately in each final state in a fiducial kinematic phase space and extrapolated to the full phase space in the invariant mass region $66 - 116~\mathrm{GeV}$. The individual cross sections are combined together and the product of the total $Z$ boson production cross section and the $Z \rightarrow \tau\tau$ branching fraction is measured to be $0.92 \pm 0.20~\mathrm{(stat)}~\pm 0.08~\mathrm{(syst)}~\pm 0.03~\mathrm{(lumi)~nb}$, in agreement with the NNLO theoretical expectations.