ИСТИНА

The potential of the LHC in the field of top quark physics is extremally high to search for rare top decays such as t -> Ws and t -> Wd which branching ratios are predicted by the Standard Model at the level of 1.77e-03 and 3.0e-05 correspondently. Really, assuming the integrated luminosity of 1.0e+04 pb^{-1} and the cross section of the 170 GeV top t tbar production equal to 700 pb at 14 TeV pp collisions, we will get ~2.2e+06 t tbar -> (l nu b + s + d)(jjb) events and among of them ~3900 t tbar -> (l nu s)(jjb), and ~70 t tbar -> (l nu d)(jjb) decays. Here and further l denotes as electron as muon either from W -> l nu decay or from successive decays of W -> tau nu, tau -> l nu nubar. The lepton reconstruction effciencies are assumed to be 90%. It seems that events of such a type are quite suitable to extract s or d jets among of huge number of b jets. A presence of an isolated charged lepton with high transverse momentum as well as high missing transverse momentum of the event would serve as a trigger, and reconstructed 3 jet mass (one of these jets should be tagged as b jet) would serve as an indicator of t tbar production. The task is to find such kinematic cuts which permit one to reject the most part of the b jets from t -> l nu b decays.