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Measurement Of The Angular Coefficients In Z Boson Events Using Electron And Muon Pairs From Data Taken At Sqrts
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Book Synopsis Measurement of the Angular Coefficients in Z-boson Events Using Electron and Muon Pairs from Data Taken at $ \sqrt{s} by :
Download or read book Measurement of the Angular Coefficients in Z-boson Events Using Electron and Muon Pairs from Data Taken at $ \sqrt{s} written by and published by . This book was released on 2016 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: The angular distributions of Drell-Yan charged lepton pairs in the vicinity of the Z-boson mass peak probe the underlying QCD dynamics of Z-boson production. This paper presents a measurement of the complete set of angular coefficients A0-7 describing these distributions in the Z-boson Collins-Soper frame. The data analysed correspond to 20.3 fb-1 of pp collisions at √s = 8 TeV, collected by the ATLAS detector at the CERN LHC. The measurements are compared to the most precise fixed-order calculations currently available (O([alpha]2s)) and with theoretical predictions embedded in Monte Carlo generators. The measurements are precise enough to probe QCD corrections beyond the formal accuracy of these calculations and to provide discrimination between different parton-shower models. A significant deviation from the (O([alpha]2s)) predictions is observed for A0 - A2. In conclusion, evidence is found for non-zero A5,6,7, consistent with expectations.
Book Synopsis Measurement of Angular Coefficients of Drell-Yan $e^+e^-$ Pairs in $p \bar{p}$ Collisions at $\sqrt{s}$ by :
Download or read book Measurement of Angular Coefficients of Drell-Yan $e^+e^-$ Pairs in $p \bar{p}$ Collisions at $\sqrt{s}$ written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we present the status of the measurement of angular distributions of final state electrons in $p \bar{p} \to \gamma^* Z \to e^+ e^- + X$ events produced in the Z boson mass region at $\sqrt{s}$ = 1.96 TeV at the Tevatron. For this analysis, we are using the full Run II dataset corresponding to 9.7$\, fb^{-1}$ of integrated luminosity collected with the D0 detector. The angular distributions as a function of the transverse momentum of the electron-positron pair are studied, and the Lam-Tung relation, valid only for a spin-1 description of the gluon is investigated. The final result will also describe the details of the production mechanism of Z bosons via quark anti-quark annihilation or quark-gluon Compton scattering.
Book Synopsis Z Boson Cross Section Measurements and Neutral Higgs Boson Search in the Di-muon Channel with the CMS Detector by : Xinmei Niu (Ph. D.)
Download or read book Z Boson Cross Section Measurements and Neutral Higgs Boson Search in the Di-muon Channel with the CMS Detector written by Xinmei Niu (Ph. D.) and published by . This book was released on 2019 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, measurements of inclusive and differential Z boson production cross sections in proton-proton collisions at [square root of] s =13 TeV with the CMS detector at Large Hadron Collider are performed with the di-muon channel. The measured total inclusive cross section times branching ratio is or(pp - ZX) x [beta](Z --> [mu][mu]) = 1870 ± 2(stat) ± 35(syst) ± 51(lumi) pb for the di-muon invariant mass in the range of 60 to 120 GeV, which is in good agreement with the next-to-next-to leading order QCD predictions. The spectra of Z boson transverse momentum, ... variable, rapidity, and the muon transverse momentum are also measured and compared with theoretical predictions. The large production cross section of Z boson and good experimental accessibility of final-state muons permit a real-time monitoring of luminosities using the counts of reconstructed Z --> [mu][mu] events. Preliminary results of counting of Z bosons as a luminometer are shown using the entire 2018 data-taking period. A search for beyond Standard Model neutral Higgs bosons decaying to two muons is also presented. No significant excess is observed. A 95% confidence level upper limit is set on ... The exclusion contour is also determined on the parameter phase space in the context of Minimal Supersymmetric Standard Mode representative benchmark scenarios.
Book Synopsis Measurement of the Production Cross-section of the Z Boson and Determination of Its Spin with the ATLAS Detector by : Shalu Solomon
Download or read book Measurement of the Production Cross-section of the Z Boson and Determination of Its Spin with the ATLAS Detector written by Shalu Solomon and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis presents the results of two measurements of the Z boson, one of the mediators of the electroweak force in the Standard Model of particle physics. The first is the measurement of the total and the differential production cross-sections of the Z boson, and the second is the determination of the spin of the particle. The measurements are made with the 6.1 fb-1 proton-proton collision data collected by the ATLAS detector in 2016 at a center of mass energy of 13 TeV with the Large Hadron Collider. The leptonic decay of the Z boson into an electron-positron pair is the channel examined. The measurements are compared with the theoretical predictions at next-to-leading order for a quantitative and a precise understanding of the process. The observed results agree with the Standard Model expectations within uncertainties. The total cross-section of Z production in the di-electron channel is measured to be 1.878 ± 0.02 (stat)_(−0.052)^(+0.045) (syst) ± 0.042 (lumi) nb and the differential cross-sections as functions of the transverse momentum and the rapidity of the Z particle match with the predictions. The angular distribution of the electrons confirms the spin 1 nature of the Z boson, also in accordance with the Standard Model." --
Book Synopsis Angular Coefficients of $Z$ Bosons Produced in $pp$ Collisions at 8 TeV and Decaying to $\mu^+\mu^-$ as a Function of Transverse Momentum and Rapidity by :
Download or read book Angular Coefficients of $Z$ Bosons Produced in $pp$ Collisions at 8 TeV and Decaying to $\mu^+\mu^-$ as a Function of Transverse Momentum and Rapidity written by and published by . This book was released on 2015 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, measurements of the five most significant angular coefficients, A0 through A4, for Z bosons produced in pp collisions at √s = 8 TeV and decaying to [mu]+[mu]- are presented as a function of the transverse momentum and rapidity of the Z boson. The integrated luminosity of the dataset collected with the CMS detector at the LHC corresponds to 19.7 fb-1. These measurements provide comprehensive information about the Z boson production mechanisms, and are compared to the QCD predictions at leading order, next-to-leading order, and next-to-next-to-leading order in perturbation theory.
Book Synopsis Measurement of the Z-Boson Branching Fraction Into Hadrons Containing Bottom Quarks by : J. Frederic Kral
Download or read book Measurement of the Z-Boson Branching Fraction Into Hadrons Containing Bottom Quarks written by J. Frederic Kral and published by . This book was released on 1990 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurement of the Z Boson Differential Cross Section in Transverse Momentum and Rapidity in Proton-proton Collisions at 8 TeV. by :
Download or read book Measurement of the Z Boson Differential Cross Section in Transverse Momentum and Rapidity in Proton-proton Collisions at 8 TeV. written by and published by . This book was released on 2015 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the Z boson differential cross section in rapidity and transverse momentum using a data sample of pp collision events at a centre-of-mass energy √s=8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The Z boson is identified via its decay to a pair of muons. The measurement provides a precision test of quantum chromodynamics over a large region of phase space. In addition, due to the small experimental uncertainties in the measurement the data has the potential to constrain the gluon parton distribution function in the kinematic regime important for Higgs boson production via gluon fusion. The results agree with the next-to-next-to-leading-order predictions computed with the fewz program. The results are also compared to the commonly used leading-order MadGraph and next-to-leading-order powheg generators.
Book Synopsis Measurement of Differential Production Cross-sections for a Z Boson in Association with B-jets in 7 TeV Proton-proton Collisions with the ATLAS Detector by :
Download or read book Measurement of Differential Production Cross-sections for a Z Boson in Association with B-jets in 7 TeV Proton-proton Collisions with the ATLAS Detector written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report measurements of differential production cross-sections of a Z boson in association with b-jets in pp collisions at √ s = 7 TeV. The data analysed correspond to an integrated luminosity of 4.6 fb-1 recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a Z boson decaying into an electron or muon pair, and containing b-jets. For events with at least one b-jet, the cross-section is presented as a function of the Z boson transverse momentum and rapidity, together with the inclusive b-jet cross-section as a function of b-jet transverse momentum, rapidity and angular separations between the b-jet and the Z boson. For events with at least two b-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum b-jets, and as a function of the Z boson transverse momentum and rapidity. Lastly, results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
Book Synopsis A Measurement of W Boson-photon and Z Boson-photon Cross Sections in the Muon Channel in 1.8 TeV Proton-antiproton Collisions by : Christopher B. Luchini
Download or read book A Measurement of W Boson-photon and Z Boson-photon Cross Sections in the Muon Channel in 1.8 TeV Proton-antiproton Collisions written by Christopher B. Luchini and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the production cross sections x decay branching ratios for W + $gamma$ and Z + $gamma$ in the muon channel in $sqrt{s}$ = 1.8 TeV p-p collisions, from 3.54 $pm$ 0.24 $pbsp{-1}$ of muon W and Z data from the CDF 1988-89 Tevatron collider run. For photons in the central region ($vertetavert $ 5.0 GeV and lepton-photon angular separation $Delta Rsb{ellsbgamma} >$ 0.7, 5 $Wsb{gamma}$ candidates and 2 $Zsb{gamma}$ candidates were observed. From these events, the $sigma cdot BR(W + gamma)$ and $sigma cdot BR(Z + gamma)$ cross sections for the muon samples are measured, and compared with Standard Model predictions. We also determined the cross section ratios, $Wsb{gamma}$/W, $Zsb{gamma}$/Z and $Wsb{gamma}/Zsb{gamma}$, which, along with the previous CDF measurement(s) of the W/Z cross section ratio provide new insight on the Standard Model, and are sensitive to anomalous couplings of the W and Z bosons. Using the $Wsb{gamma}$ and $Zsb{gamma}$ absolute cross section measurements, the absence of an excess of hard photons accompanying W and Z boson production enables us to obtain direct limites on anomalous $WWsb{gamma}$, $ZZsb{gamma}$ and $Zsb{gammagamma}$ couplings. For saturation of unitarity, these experimental limits impose constraints on possible internal (composite) structure for the W and Z bosons with compositeness scale sensitivity up to $Lambdasb{W} sim$ 1 TeV and $Lambdasb{Z} sim$ 250-500 GeV, respectively. These compositeness scale limits probe the possible internal structure of the W to ${sim}
Book Synopsis Measurement of Electroweak WZ Boson Production and Search for New Physics at Sqrt(s) by : Kenneth David Long
Download or read book Measurement of Electroweak WZ Boson Production and Search for New Physics at Sqrt(s) written by Kenneth David Long and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the simultaneous production of a W and a Z boson (WZ production) via vector boson scattering is presented. The measurement is performed in the leptonic decay modes WZ --> lvl'l', where l, l'indicate an electron or muon. The analysis is based on a data sample of proton-proton collisions at sqrt(s) = 13 TeV at the CERN Large Hadron Collider collected with the Compact Muon Solenoid detector and corresponding to an integrated luminosity of 35.9 fb-1. The WZ plus two jet production cross section is measured in fiducial regions with enhanced contributions from electroweak (EW) production and found to be consistent with standard model predictions. The EW WZ production in association with two jets is measured with an observed (expected) significance of 2.2 (2.5) standard deviations. Results are also interpreted in terms of physics beyond the standard model modifying the interactions of the W and Z bosons. Constraints on charged Higgs boson production and on anomalous quartic gauge couplings in terms of dimension-eight effective field theory operators are presented.
Book Synopsis Diffractively Produced Z Bosons in the Muon Decay Channel in P-pbar Collisions at S**(1/2) by : Tamsin L. Edwards
Download or read book Diffractively Produced Z Bosons in the Muon Decay Channel in P-pbar Collisions at S**(1/2) written by Tamsin L. Edwards and published by . This book was released on 2006 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first analysis of diffractively produced Z bosons in the muon decay channel is presented, using data taken by the D0 detector at the Tevatron at {radical}s = 1.96 TeV. The data sample corresponds to an integrated luminosity of 109 pb{sup -1}. The diffractive sample is defined using the fractional momentum loss {zeta} of the intact proton or antiproton measured using the calorimeter and muon detector systems. In a sample of 10791 (Z/{gamma})* {yields} {mu}{sup +}{mu}{sup -} events, 24 diffractive candidate events are found with {zeta}
Book Synopsis Measurement of the Z? Production Cross Section in Pp Collisions at 8 TeV and Search for Anomalous Triple Gauge Boson Couplings by :
Download or read book Measurement of the Z? Production Cross Section in Pp Collisions at 8 TeV and Search for Anomalous Triple Gauge Boson Couplings written by and published by . This book was released on 2015 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cross section for the production of Z? in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb-1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. Furthermore, the differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. These observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. As a result, limits on anomalous triple gauge couplings of ZZ? and Z?? are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.
Book Synopsis Measurement of the Boson Z Differential Cross-section in Transverse Momentum in the Electron-positron Channel with the ATLAS Detector at LHC by : Homero Martinez
Download or read book Measurement of the Boson Z Differential Cross-section in Transverse Momentum in the Electron-positron Channel with the ATLAS Detector at LHC written by Homero Martinez and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Z Boson Asymmetry Measurements at the Tevatron by :
Download or read book Z Boson Asymmetry Measurements at the Tevatron written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of the forward-backward asymmetry (A_fb) in dilepton pair decays of Z bosons produced in ppbar collisions using the full Tevatron dataset. The CDF experiment extracts a value for the effective weak mixing angle parameter sin^{2}\theta^{l}_{eff} of 0.2315 +/- 0.0010 from the A_fb distribution of dimuon events in 9.2 fb^{-1} of integrated luminosity. From dielectron events in 9.7 fb^{-1} of data, the D0 experiment finds sin^{2}\theta^{l}_{eff} = 0.23106 +/- 0.00053, the world's most precise measurement of sin^{2}\theta^{l}_{eff} from hadron colliders and with light quark couplings.
Book Synopsis A Measurement of the Z Boson Transverse Momentum Distribution, and of the ZZ and WZ Production Cross Sections Using 7.3-8.6 Fb$^{-1}$ of $p\bar{p}$ Collisions at $\sqrt{s}$ by :
Download or read book A Measurement of the Z Boson Transverse Momentum Distribution, and of the ZZ and WZ Production Cross Sections Using 7.3-8.6 Fb$^{-1}$ of $p\bar{p}$ Collisions at $\sqrt{s}$ written by and published by . This book was released on 2011 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two analyses are performed with the large samples of dielectron and dimuon events collected by the D0 experiment at the Fermilab Tevatron $p\bar{p}$ collider. The dilepton transverse momentum ($p_T$) distribution in $Z/\gamma^* → \ell^+\ell^-$ production is a powerful probe of Quantum chromodynamics. Until now, this distribution has been measured with limited precision. An alternative variable, $\phi^*_\eta$, is proposed due to its relatively low susceptibility to detector effects. The $\phi^*_\eta$, distribution of events with $Z/\gamma^* → \ell^+\ell^-$ invariant masses between 70 and 110 GeV, is measured in three bins of dilepton rapidity. This measurement, with 7.3 fb$^{-1}$ of data, is significantly more precise than previous measurements of the $p_T$ distribution. A state-of-the-art QCD Monte Carlo program is in modest agreement with the data. Using 8.6 fb$^{-1}$ of data, the $ZZ/\gamma^* → \nu\bar{\nu}\ell^+\ell^-$ and $WZ/\gamma^* → \ell\nu\ell^+\ell^-$ processes are studied, yielding production cross sections of, $\sigma(p\bar{p} \rightarrow ZZ/\gamma^*)$ = 1.64 $\pm$ 0.46 p b and $\sigma(p\bar{p} \rightarrow WZ/\gamma^*)$ = 4.46 $\pm$ 0.64 pb, for $Z/\gamma^* → \ell^+\ell^-$ invariant masses between 60 and 130 GeV. These are in agreement with Standard Model predictions.
Book Synopsis Production of Gauge Bosons at the Tevatron by :
Download or read book Production of Gauge Bosons at the Tevatron written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The CDF and D0 collaborations have used recent data taken at the Tevatron to perform QCD tests with W and Z bosons decaying leptonically. D0 measures the production cross section times branching ratio for W and Z bosons and determines the branching ratio B(W[yields] l[nu])= (10.43[+-] 0.44)% (l= e, [mu]). This also gives an indirect measurement of the total width of the W boson:[Gamma][sub W]= 2.16[+-] 0.09 GeV. The W cross section times branching ratio into tau leptons is measured to be[sigma]([anti p]p[yields] W+ X)B(W[yields][tau][nu])= 2.38[+-]0.13 nb, from which the ratio of the coupling constants is determined: g[sub[tau]][sup W]/g[sub e][sup W]= 1.004[+-] 0.019[+-] 0.026. D0's measurement of the differential d[sigma]/dP[sub T] distribution for the Z boson decaying to electrons, discriminates between different phenomenologic vector boson production models. CDF measures the cross section for the Drell-Yan continuum, and extracts improved limits on compositeness scales for quarks and leptons of[Lambda][sub ql][approximately] 3 - 6 TeV, depending on the model. Studies of W+ Jet production at CDF and D0 find that the QCD prediction underestimates the production rate of W+ 1 Jet events by about a factor of 2 as measured by both collaborations.
Book Synopsis Search for Heavy Gauge W' Boson in Events with an Energetic Lepton and Large Missing Transverse Momentum at Sqrt(s) by :
Download or read book Search for Heavy Gauge W' Boson in Events with an Energetic Lepton and Large Missing Transverse Momentum at Sqrt(s) written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for W' bosons in events with an electron or muon and large missing transverse momentum, using proton-proton collision data at sqrt(s) = 13 TeV collected with the CMS detector in 2015 and corresponding to an integrated luminosity of 2.3 inverse femtobarns. No evidence of an excess of events relative to the standard model expectations is observed. For a W' boson described by the sequential standard model, upper limits at 95% confidence level are set on the product of the production cross section and branching fraction and lower limits are established on the new boson mass. Masses below 4.1 TeV are excluded combining electron and muon decay channels, significantly improving upon the results obtained with the 8 TeV data. Exclusion limits at 95% confidence level on the product of the W' production cross section and branching fraction are also derived in combination with the 8 TeV data. Finally, exclusion limits are set for the production of generic W' bosons decaying into this final state using a model-independent approach.
