ATLAS sensitivity to Wtb anomalous couplings in top quark decays

Understand

We study the sensitivity of the ATLAS experiment to Wtb anomalous couplings in top pair production with semileptonic decay, pp -> t tbar -> W+ b W- bbar, with one of the W bosons decaying leptonically and the other hadronically.

• Several observables are examined, including the W helicity fractions and new quantities recently introduced, such as the ratios of helicity fractions and some angular asymmetries defined in the W rest frame.
• The dependence on anomalous couplings of all these observables has been previously obtained.
• In this work we show that some of the new observables also have smaller systematic uncertainties than the helicity fractions, with a dependence on anomalous couplings similar or stronger than for helicity fractions.