Daniela Victorita Goldstein

The top-quark pair production cross section in 7 TeV center-of-mass energy proton–proton collisions is measured using data collected by the CMS detector at the LHC. The measurement uses events with one jet identified as a hadronically decaying τ lepton and at least four additional energetic jets, at least one of which is identified as coming from a b quark. The analyzed data sample corresponds to an integrated luminosity of 3.9 fb−1 recorded by a dedicated multijet plus hadronically decaying τ trigger. A neural network has been developed to separate the top-quark pairs from the W+jets and multijet backgrounds. The measured value of $\sigma_{\mathrm{t}\bar{\mathrm{t}}} = 152\pm 12\,(\mbox{stat.})\pm 32\,(\mbox{syst.})\pm3\,(\mbox{lum.})\ \mbox{pb}$ is consistent with the standard model predictions.

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 [Formula: see text] and is in agreement with other measurements and with the Standard Model prediction.