Simultaneous Measurements Of The Tt U00af W W And Z U2192 Production Cross Sections In Pp Collisions At S

Simultaneous Measurements of the Tt{u00AF} , W+W- , and Z/?*{u2192}?? Production Cross-sections in Pp Collisions at S

Simultaneous measurements of the tt¯, W+W–, and Z/?*→?? production cross-sections using an integrated luminosity of 4.6 fb–1 of pp collisions at √s=7 TeV collected by the ATLAS detector at the LHC are presented. Events are selected with two high transverse momentum leptons consisting of an oppositely charged electron and muon pair. The three processes are separated using the distributions of the missing transverse momentum of events with zero and greater than zero jet multiplicities. Measurements of the fiducial cross-section are presented along with results that quantify for the first time the underlying correlations in the predicted and measured cross-sections due to proton parton distribution functions. Results indicate that the correlated next-to-leading-order predictions for tt¯ and Z/?*→?? underestimate the data, while those at next-to-next-to-leading-order generally describe the data well. The full cross-sections are measured to be ?(tt¯)=181.2 ± 2.8+9.7–9.5 ± 3.3 ± 3.3 pb, ?(W+W–) = 53.3 ± 2.7+7.3–8.0 ± 1.0 ± 0.5 pb, and ?(Z/?*→??) = 1174 ± 24+72–87 ± 21 ± 9 pb, where the cited uncertainties are due to statistics, systematic effects, luminosity and the LHC beam energy measurement, respectively. The W+W– measurement includes the small contribution from Higgs boson decays, H → W+W–.

Measurement of the Tt, WW and Z -- [tau Tau] Production Cross Sections in Pp Collisions at [square Root of S]

Measurement of the Tt, WW and Z -] Tautau Production Cross Sections in P Anti-p Collisions at S**(1/2)

In this thesis we present a new technique to analyze events containing two highly energetic leptons, as a probe of the Standard Model. The philosophy is to consider the data in a more global way, as opposed to the more traditional process dependent approach of extracting a given signal over the expected backgrounds by using various kinematical requirements. We use our global technique to simultaneously measure the cross sections of the main Standard Model processes; the t{bar t}, WW and Z → [tau][tau] production from p{bar p} collisions at √s = 1.96 TeV in the CDF detector at Fermilab. We select events by requiring they contain two highly energetic leptons (e[mu], ee, or [mu][mu]), and make no other kinematic requirements, except for the ee and [mu][mu] channels. We then use a likelihood fit of the data in the two-dimensional phase space defined by the missing transverse energy (E{sub T}) and the number of jets in the event (N{sub jet}), to the expected Standard Model distributions, to simultaneously extract the production cross-sections of the main process contributing to our dilepton sample.