Measurement of the top quark mass in the alljets channel.

The top quark, the upper quark of the third fermion family, was discovered by CDF and DO collaborations at Fermilab Tevatron collider in 1995. Both, CDF and DO experiments measured the top quark properties, tt production cross section and top quark mass mass, in various decay channels. This thesis describes the measurement of the top quark mass in alljets final states using data collected by the DO detector during Run I in 1992 - 1996. The alljets channel has, compared to other tt decay modes, large branching ratio but it is characteristic by enormous QCD background. Both top quarks decay to the b quark and W boson, and both W bosons then decay to quarks forming fully hadronic final states. Such events thus should contain only jets with no isolated leptons.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Study of the normalized transverse momentum distribution of WW bosons produced in ppˉp \bar p collisions at s\sqrt {s} = 1.96 TeV

International audienceWe present a study of the normalized transverse momentum distribution of W bosons produced in pp¯ collisions, using data corresponding to an integrated luminosity of 4.35  fb-1 collected with the D0 detector at the Fermilab Tevatron collider at s=1.96  TeV. The measurement focuses on the transverse momentum region below 15 GeV, which is of special interest for electroweak precision measurements; it relies on the same detector calibration methods which were used for the precision measurement of the W boson mass. The measured distribution is compared to different QCD predictions and a procedure is given to allow the comparison of any further theoretical models to the D0 data