Single-top in Wt associated production at ATLAS

Within the context of the top quark physics a specific interest is to be devoted to the production of single top quarks, since only electroweak (EW) couplings are involved, which make this production a very important framework to identify and test in detail some slight deviations from the SM predictions which might appear. The Wt channel is the second most important contribute to the total single top production. It is characterized by the presence of a single top and a spectator W boson in the final states. The subsequent weak decay of the top is cause of an ambiguity between two W bosons which makes the top very difficult to reconstruct univocally. For this reason the possibility of using a kinematic fitting procedure both to identify the signal events and the top quark within the event itself is under way of study. The channel is analyzed in the so called semileptonic decay mode of the two W bosons, leading to a final states composition of one b-jet, two light jets, one lepton and missing transverse energy. This particular production channel raises interests in itself, as a major challenge offered to the experimentalist by its detection on one hand, and also due to the fact that it represents an important background to the isolation of signals from a charged Higgs on the other. The kinematics of the Wt production mode are shown, and the choices regarding the cuts to extract the Wt signal from its various backgrounds, the problems encountered and some first results obtained are presented and discussed.