Measurement of the single-top t-channel charge ratio at 8 TeV

This note presents a measurement of the top and anti-top production ratio in single-top $t$-channel processes at 8 TeV with the CMS detector at the LHC. A selection exploiting the $t$-channel topology is performed. Events are selected with the top decaying either into an inclusive muon or electron. The main backgrounds are evaluated through data-driven techniques. The distribution of pseudorapidity of the recoil quark is exploited to extract the signal simultaneously in the events with positively and negatively charged leptons. The separate top and anti-top cross sections measurements yield $\sigma_{t\textrm{-ch., top}} = 49.9 \pm 9.1$ $\mathrm{pb}$ and $\sigma_{t\textrm{-ch., anti-top}} = 28.3 \pm 5.5$ $\mathrm{pb}$ respectively. The measured ratio is $R_{t\textrm{-ch.}}=\sigma_{t\textrm{-ch., top}}/\sigma_{t\textrm{-ch., anti-top}}=1.76 \pm 0.27$, in agreement with the standard model predictions.