A measurement of the top quark pair production cross section in the final state with a hadronically decaying tau lepton and jets is presented. The analysis is based on proton–proton collision data recorded by the ATLAS experiment at the LHC, with a centre-of-mass energy of 7 TeV. The data sample corresponds to an integrated luminosity of 1.67 fb−1. The cross section is measured to be σt ¯t = 194 ± 18 (stat.) ± 46 (syst.) pb and is in agreement with other measurements and with the Standard Model prediction.Facultad de Ciencias Exactas