We search for CP violation in a sample of 4.7 x 10{sup 4} singly Cabibbo suppressed D{sup 0} {yields} K{sup +} K{sup -} {pi}{sup +}{pi}{sup -} decays and 1.8(2.6) x 10{sup 4} D{sub (s)}{sup +} {yields} K{sub S}{sup 0} K{sup +} {pi}{sup +} {pi}{sup -} decays. CP violation is searched for in the difference between the T-odd asymmetries, obtained using triple product correlations, measured for D and {bar D} decays. The measured CP violation parameters are A{sub T}(D{sup 0}) = (1.0 {+-} 5.1(stat) {+-} 4.4(syst)) x 10{sup -3}, A{sub T}(D{sup +}) = (-11.96 {+-} 10.04(stat) {+-} 4.81(syst)) x 10{sup -3} and A{sub T}(D{sub s}{sup +}) = (-13.57 {+-} 7.67(stat) {+-} 4.82(syst)) x 10{sup -3}. This search for CP violation showed that the T-odd correlations are a powerful tool to measure the CP violating observable A{sub T}. The relative simplicity of an analysis based on T-odd correlations and the high quality results that can be obtained, allow to consider this tool as fundamental to search for CP violation in four-body decays. Even if the CP violation has not been found, excluding any New Physics effect to the sensitivity of about 0.5%, it is still worth to search for CP violation in …

The subject of this thesis is the search for a standard model Higgs boson decaying to a pair of W bosons that in turn decay leptonically, H {yields} W{sup +}W{sup -} {yields} {bar {ell}}{nu}{ell}{bar {nu}}. This search is performed considering events produced in p{bar p} collisions at {radical}s = 1.96 TeV, where two oppositely charged lepton candidates (e{sup +}e{sup -}, e{sup {+-}}{mu}{sup {-+}}, or {mu}{sup +}{mu}{sup -}), and missing transverse energy, have been reconstructed. The data were collected with the D0 detector at the Fermilab Tevatron collider, and are tested against the standard model predictions computed for a Higgs boson with mass in the range 115-200 GeV. No excess of events over background is observed, and limits on Standard Model Higgs boson production are determined. An interpretation of these limits within the hypothesis of a fourth-generation extension to the standard model is also given. The overall analysis scheme is the same for the three dilepton pairs being considered (e{sup +}e{sup -}, e{sup {+-}}{mu}{sup {-+}}, or {mu}{sup +}{mu}{sup -}); this thesis, however, describes in detail the study of the dimuon final state.