Simultaneous Measurements of the Tt{u00AF} , W+W- , and Z/?*{u2192}?? Production Cross-sections in Pp Collisions at S PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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–.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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–.
Author: Publisher: ISBN: Category : Languages : en Pages : 204
Book Description
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$ar{t}$, WW and Z → ?? production from p$ar{p}$ collisions at √s = 1.96 TeV in the CDF detector at Fermilab. We select events by requiring they contain two highly energetic leptons (e?, ee, or ??), and make no other kinematic requirements, except for the ee and ?? channels. We then use a likelihood fit of the data in the two-dimensional phase space defined by the missing transverse energy (ET) and the number of jets in the event (Njet), to the expected Standard Model distributions, to simultaneously extract the production cross-sections of the main process contributing to our dilepton sample.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A measurement of inclusive W and Z production cross sections in pp collisions at sqrt(s)=7 TeV is presented. The electron and muon decay channels are analyzed in a data sample collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 inverse picobarns. The measured inclusive cross sections are sigma(pp-> WX) B(W-> l nu) = 10.30 +/- 0.02 (stat.) +/- 0.10 (syst.) +/- 0.10 (th.) +/- 0.41 (lumi.) nb and sigma(pp -> ZX) B(Z-> l+̂l-̂) = 0.974 +/- 0.007 (stat.) +/- 0.007 (syst.) +/- 0.018 (th.) +/- 0.039 (lumi.) nb, limited to the dilepton invariant mass range 60 to 120 GeV. The luminosity-independent cross section ratios are [sigma(pp->WX) B(W-> l nu)]/[sigma(pp-> ZX) B(Z->l+̂l-̂)] = 10.54 +/- 0.07 (stat.) +/- 0.08 (syst.) +/- 0.16 (th.) and [sigma(pp->W+̂X) B(W+̂ -> l+̂nu)] / [sigma(pp->W-̂ X) B(W-̂ -> l-̂ nu)] = 1.421 +/- 0.006 (stat.) +/- 0.014 (syst.) +/- 0.029 (th.). The measured values agree with next-to-next-to-leading order QCD cross section calculations based on recent parton distribution functions.
Author: Publisher: ISBN: Category : Languages : en Pages : 38
Book Description
Measurements of inclusive W and Z boson production cross sections in pp collisions at sqrt(s)=7 TeV are presented, based on 2.9 inverse picobarns of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give sigma(pp to WX) times B(W to muon or electron + neutrino) = 9.95 \pm 0.07(stat.) \pm 0.28(syst.) \pm 1.09(lumi.) nb and sigma(pp to ZX) times B(Z to oppositely charged muon or electron pairs) = 0.931 \pm 0.026(stat.) \pm 0.023(syst.) \pm 0.102(lumi.) nb. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reported.
Author: Stephanie Akemi Brandt Publisher: ISBN: Category : Languages : en Pages : 160
Book Description
Measurements of W and Z boson production cross sections in pp collisions at [square root] s = 5.02TeV and [square root] s = 13TeV are presented. Data was collected by the CMS experiment at the LHC during low-pileup data taking periods in 2017. The corresponding integrated luminosity for the data is 299.1 ± 5 pb−1 ( [square root] s = 5.02TeV) and 199.3 ± 4 pb−1 ( [square root] s = 13TeV), with an average number of pile-up interactions [[mu] = 3 ([mu] = 2). Cross sections and cross section ratios are reported, with final states in electron and muon channels.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cross sections for the production of a Z boson in association with jets in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$=8 TeV are measured using a data sample collected by the CMS experiment at the LHC corresponding to 19.6 inverse femtobarns. Differential cross sections are presented as functions of up to three observables that describe the jet kinematics and the jet activity. Correlations between the azimuthal directions and the rapidities of the jets and the Z boson are studied in detail. The predictions of a number of multileg generators with leading or next-to-leading order accuracy are compared with the measurements. The comparison shows the importance of including multi-parton contributions in the matrix elements and the improvement in the predictions when next-to-leading order terms are included.
Author: Publisher: ISBN: Category : Languages : en Pages : 39
Book Description
The production of a Z boson, decaying into two leptons and produced in association with one or more b jets, is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV. The data were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 5 fb-1. The Z(ll) + b-jets cross sections (where ll = [mu][mu] or ee) are measured separately for a Z boson produced with exactly one b jet and with at least two b jets. In addition, a cross section ratio is extracted for a Z boson produced with at least one b jet, relative to a Z boson produced with at least one jet. The measured cross sections are compared to various theoretical predictions, and the data favour the predictions in the five-flavour scheme, where b quarks are assumed massless. The kinematic properties of the reconstructed particles are compared with the predictions from the MadGraph event generator using the pythia parton shower simulation.
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Author: ![Measurement of W and Z Boson Production Cross Sections in Proton-proton Collisions at [square Root] S PDF](https://books.google.com/books/content/images/frontcover/QLpjzgEACAAJ?fife=w80-h100)
Author: Stephanie Akemi Brandt
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Author: Ksenia Gasnikova