Measurement of the Cross-section for B-jets Produced in Association with a Z Boson at Sqrt(s) PDF Download

Author: Aaron Colin Bundock
Publisher:
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Languages : en
Pages :

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Author:
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Languages : en
Pages : 39

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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.

Author: Giovanni Zevi Della Porta
Publisher:
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Languages : en
Pages : 0

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This dissertation presents a measurement of the W+b-jets (pp --> W+bb+X) production cross-section in proton--proton collisions at a center-of-mass energy of 7 TeV at the LHC. The results are based on data corresponding to an integrated luminosity of 4.6 fb-1, collected with the ATLAS detector.

Author: John Campbell
Publisher: Oxford University Press
ISBN: 0191014990
Category : Science
Languages : en
Pages : 761

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The Black Book of Quantum Chromodynamics is an in-depth introduction to the particle physics of current and future experiments at particle accelerators. The book offers the reader an overview of practically all aspects of the strong interaction necessary to understand and appreciate modern particle phenomenology at the energy frontier. It assumes a working knowledge of quantum field theory at the level of introductory textbooks used for advanced undergraduate or in standard postgraduate lectures. The book expands this knowledge with an intuitive understanding of relevant physical concepts, an introduction to modern techniques, and their application to the phenomenology of the strong interaction at the highest energies. Aimed at graduate students and researchers, it also serves as a comprehensive reference for LHC experimenters and theorists. This book offers an exhaustive presentation of the technologies developed and used by practitioners in the field of fixed-order perturbation theory and an overview of results relevant for the ongoing research programme at the LHC. It includes an in-depth description of various analytic resummation techniques, which form the basis for our understanding of the QCD radiation pattern and how strong production processes manifest themselves in data, and a concise discussion of numerical resummation through parton showers, which form the basis of event generators for the simulation of LHC physics, and their matching and merging with fixed-order matrix elements. It also gives a detailed presentation of the physics behind the parton distribution functions, which are a necessary ingredient for every calculation relevant for physics at hadron colliders such as the LHC, and an introduction to non-perturbative aspects of the strong interaction, including inclusive observables such as total and elastic cross sections, and non-trivial effects such as multiple parton interactions and hadronization. The book concludes with a useful overview contextualising data from previous experiments such as the Tevatron and the Run I of the LHC which have shaped our understanding of QCD at hadron colliders.

Author: Kiran Joshi
Publisher: Springer
ISBN: 3319196537
Category : Science
Languages : en
Pages : 188

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This thesis contains new research in both experimental and theoretical particle physics, making important contributions in each. Two analyses of collision data from the ATLAS experiment at the LHC are presented, as well as two phenomenological studies of heavy coloured resonances that could be produced at the LHC. The first data analysis was the measurement of top quark-antiquark production with a veto on additional jet activity. As the first detector-corrected measurement of jet activity in top-antitop events it played an important role in constraining the theoretical modelling, and ultimately reduced these uncertainties for ATLAS's other top-quark measurements by a factor of two. The second data analysis was the measurement of Z+2jet production and the observation of the electroweak vector boson fusion (VBF) component. As the first observation of VBF at a hadron collider, this measurement demonstrated new techniques to reliably extract VBF processes and paved the way for future VBF Higgs measurements. The first phenomenological study developed a new technique for identifying the colour of heavy resonances produced in proton-proton collisions. As a by-product of this study an unexpected and previously unnoticed correlation was discovered between the probability of correctly identifying a high-energy top and the colour structure of the event it was produced in. The second phenomenological study explored this relationship in more detail, and could have important consequences for the identification of new particles that decay to top quarks.

Author: Wang Wei
Publisher: World Scientific
ISBN: 9811207410
Category : Science
Languages : en
Pages : 576

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The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.

Author:
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Languages : en
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Measurements of the associated production of a Z boson with at least one jet originating from a b quark in proton-proton collisions at $\sqrt{s}$ = 8 TeV are presented. Differential cross sections are measured with data collected by the CMS experiment corresponding to an integrated luminosity of 19.8 inverse femtobarns. Z bosons are reconstructed through their decays to electrons and muons. Cross sections are measured as a function of observables characterizing the kinematics of the b jet and the Z boson. Ratios of differential cross sections for the associated production with at least one b jet to the associated production with any jet are also presented. The production of a Z boson with two b jets is investigated, and differential cross sections are measured for the dijet system. Results are compared to theoretical predictions, testing two different flavour schemes for the choice of initial-state partons.

Author:
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ISBN:
Category :
Languages : en
Pages : 31

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A measurement of the b jet production cross section is presented for events containing a Z boson produced in p{bar p} collisions at √s = 1.96 TeV, using data corresponding to an integrated luminosity of 2 fb−1 collected by the CDF II detector at the Tevatron. Z bosons are selected in the electron and muon decay modes. Jets are considered with transverse energy E{sub T} > 20 GeV and pseudorapidity.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

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The cross section for jets from b quarks produced simultaneously with a W boson has been measured in p{bar p} collision data from 1.9 fb−1 of integrated luminosity recorded by the CDF II detector at the Tevatron. Jets consistent with the decay of long-lived hadrons are selected by identifying a displaced decay vertex. The invariant mass of the charged particle tracks associated with the vertex is sensitive to the flavor of the decaying hadron and is used to determine the fraction of jets from b-quark production. We measure a b-jet cross section of 2.74 ± 0.27(stat.) ± 0.42(syst.) pb in association with one flavor of leptonic W boson decay over a limited kinematic phase space.

Author:
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Category :
Languages : en
Pages : 8

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Book Description
The cross section for jets from b quarks produced simultaneously with a W boson has been measured in p{bar p} collision data from 1.9 fb−1 of integrated luminosity recorded by the CDF II detector at the Tevatron. Jets consistent with the decay of long-lived hadrons are selected by identifying a displaced decay vertex. The invariant mass of the charged particle tracks associated with the vertex is sensitive to the flavor of the decaying hadron and is used to determine the fraction of jets from b-quark production. We measure a b-jet cross section of 2.74 ± 0.27(stat.) ± 0.42(syst.) pb in association with one flavor of leptonic W boson decay over a limited kinematic phase space.