Prospect for Single Top Quark Cross-Section Measurements

At the LHC, the single top quarks will be produced at a third of the rate of top quark pairs. With more than two million single top quark events produced every year during the low luminosity run, a precise determination of all contributions to the total single top quark cross section seems achievable. Comparison between the measured cross section and the theoretical prediction will provide a crucial test of the Standard Model. These measurements will lead to direct measurement of Vtb at the few percent level of precision, and constitute a powerful probe for new physics, via the search for evidence of anomalous couplings to the top quark or the measurements of additional boson contributions to single top quark production. The single top quark production mechanism proceeds through three different sub-processes resulting in distinct final states, topologies and backgrounds. Given the level of backgrounds affecting the individual selections and the importance of the systematic uncertainties, the use of sophisticated methods appears mandatory to unambigiously observe each process and determine precisely the corresponding cross sections. This report presents the methods developed to optimize the selection of single top quark events in the three channels and establishes the ATLAS potential for the cross section measurements for the early data period and for a 30 fb^−1 low luminosity run.