This thesis deals with the search for electroweak production of the top quark (single top in $s$ and $t$ channels) in ppbar collisions at the Tevatron in the D0 eperiment with an integrated luminosity of 370~pb$^{-1}$. This process has not been obbserved yet. Identifying the bottom qurk jet from the top decay plays a major role in this analysis. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton and missing energy. A multivariate analysis is needed to separate the signal from the main backgrounds. The achieved sensitivity is not sufficient enough to reach observation and we computed upper limits at the 95% confidence level of 5~pb ($s$-channel) and 4.3~pb ($t$-channel) on single top production cross-sections.
Electroweak production of the top quark in the Run II of the Dzero experiment