Measurement of the $Z \to \tau\tau$ production cross-section in proton-proton collisions at $\sqrt{s}$ = 7 TeV with the ATLAS detector

The first measurement of the inclusive cross-section of the Z boson decaying to two tau leptons was measured with the ATLAS detector at the LHC. The data sample in this analysis represents an integrated luminosity of 35 pb$^{−1}$ of proton-proton collisions at a center of mass energy of $\sqrt{s}$ = 7 TeV. Separate measurements were performed in four decay modes based on how the two tau leptons decay: to hadrons and an electron, to hadrons and a muon, to an electron and a muon, and to two muons. In all four final states, inclusive cross-section measurements were made both in the fiducial region of the ATLAS detector where acceptance is high and in the full phase space, restricted to the mass range of [66, 116] GeV. The measurements from the four individual channels were then combined to yield the combined $Z \to \tau \tau$ cross-section of 970 $\pm$ 70 (stat.) $\pm$ 60 (sys.) $\pm$ 30 (lumi.) pb.