A Measurement Of The T T Bar Production Cross Section In Proton Antiproton Collisions At Sqrt S

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A Measurement Of The Production Cross Section Of Tt Pairs In Proton Antiproton Collisions At Square Root S

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Author : Henri Bachacou
language : en
Publisher:
Release Date : 2004

A Measurement Of The Production Cross Section Of Tt Pairs In Proton Antiproton Collisions At Square Root S written by Henri Bachacou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

Measurement Of The Ttbar Production Cross Section In The Met Jets Channel At Cdf

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Author :
language : en
Publisher:
Release Date : 2008

Measurement Of The Ttbar Production Cross Section In The Met Jets Channel At Cdf written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.

This thesis is focused on an inclusive search of the t{bar t} --> E{sub T} + jets decay channel by means of neural network tools in proton antiproton collisions at (square root)s = 1.96 TeV recorded by the Collider Detector at Fermilab (CDF). At the Tevatron p{bar p} collider top quarks are mainly produced in pairs through quark-antiquark annihilation and gluon-gluon fusion processes; in the Standard Model description, the top quark then decays to a W boson and a b quark almost 100% of the times, so that its decay signatures are classified according to the W decay modes. When only one W decays leptonically, the t{bar t} event typically contains a charged lepton, missing transverse energy due to the presence of a neutrino escaping from the detector, and four high transverse momentum jets, two of which originate from b quarks. In this thesis we describe a t{bar t} production cross section measurement which uses data collected by a 'multijet' trigger, and selects this kind of top decays by requiring a high-P{sub T} neutrino signature and by using an optimized neural network to discriminate top quark pair production from backgrounds. In Chapter 1, a brief review of the Standard Model of particle physics will be discussed, focusing on top quark properties and experimental signatures. In Chapter 2 will be presented an overview of the Tevatron accelerator chain that provides p{bar p} collisions at the center-of-mass energy of (square root)s = 1.96 TeV, and proton and antiproton beams production procedure will be discussed. The CDF detector and its components and subsystems used for the study of p{bar p} collisions provided by the Tevatron will be described in Chapter 3. Chapter 4 will detail the reconstruction procedures used in CDF to detect physical objects exploiting the features of the different detector subsystems. Chapter 5 will provide an overview of the main concepts regarding Artificial Neural Networks, one of the most important tools we will use in the analysis. Chapter 6 will be devoted to the description of the main characteristics of the t{bar t} --> E{sub T} + jets decay channel used to train our neural network to discriminate the top pair production from background processes. We will discuss the event selection method and the technique used for background prediction, that will rely on b-jets identification rate parameterization. Finally, Chapter 7 will provide a description of the final data sample and a detailed discussion of the systematic uncertainties before determining the cross section measurement by means of a likelihood maximization.

Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S

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Author :
language : en
Publisher:
Release Date : 2010

Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.

We present a measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to 1.7 fb−1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct t{bar t} events in the lepton+jets channel, consisting of e[nu]+jets and [mu][nu]+jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ('soft electron tags'). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 ± 3 events, corresponding to a cross section of [sigma]{sub t{bar t}} = 7.8 ± 2.4 (stat) ± 1.6 (syst) ± 0.5 (lumi) pb. We assume a top-quark mass of 175 GeV/c2. This is the first measurement of the t{bar t} cross section with soft electron tags in Run II of the Tevatron.

A Measurement Of The T T Bar Production Cross Section In Proton Antiproton Collisions At Sqrt S

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Author : Markus Klute
language : en
Publisher:
Release Date : 2004

A Measurement Of The T T Bar Production Cross Section In Proton Antiproton Collisions At Sqrt S written by Markus Klute and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

Scientific And Technical Aerospace Reports

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Author :
language : en
Publisher:
Release Date : 1992

Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Aeronautics categories.

Measurement Of The Ttbar Production Cross Section In 2 Fb 1 Of Ppbar Collisions At Sqrt S

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Author :
language : en
Publisher:
Release Date : 2009

Measurement Of The Ttbar Production Cross Section In 2 Fb 1 Of Ppbar Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.

We present a measurement of the t{bar t} production cross section in p{bar p} collisions at (square root)s = 1.96 TeV using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with t{bar t} decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF Run II data sample corresponding to 2 fb−1 of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of 79.5 ± 5.3 events, we measure a production cross section of 9.1 ± 1.6 pb.

Top Physics

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Author :
language : en
Publisher:
Release Date : 2005

Top Physics written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.

We present a measurement of the t{bar t} production cross section using 194 pb−1 of CDF II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes 100% t --> Wb branching fraction. Events consistent with t{bar t} decay are found by identifying jets containing heavy flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 20 candidate events and an expected background of 9.5 " 1.1 events, we measure a production cross section of 5.3 " 3.3{sub -1.0}{sup +1.3} pb, in agreement with the standard model.

Measurement Of The Ttbar Production Cross Section In The All Jets Final State In Pp Collisions At Sqrt S

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Author :
language : en
Publisher:
Release Date : 2015

Measurement Of The Ttbar Production Cross Section In The All Jets Final State In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.

The cross section for tt production in the all-jets final state is measured in pp collisions at a centre-of-mass energy of 8 TeV at the LHC with the CMS detector, in data corresponding to an integrated luminosity of 18.4 fb-1. The inclusive cross section is found to be 275.6 ±6.1 (stat) ± 37.8 (syst) ± 7.2 (lumi) pb. The normalized differential cross sections are measured as a function of the top quark transverse momenta, pT, and compared to predictions from quantum chromodynamics. The results are reported at detector, parton, and particle levels. In all cases, the measured top quark pT spectra are significantly softer than theoretical predictions.

A Measurement Of The Tt Production Cross Section In Proton Antiproton Collisions At Square Root S

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Author : Markus Klute
language : en
Publisher:
Release Date : 2004

A Measurement Of The Tt Production Cross Section In Proton Antiproton Collisions At Square Root S written by Markus Klute and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2

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Author : Markus Klute
language : en
Publisher:
Release Date : 2004

A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2 written by Markus Klute and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

A preliminary measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV is presented. The {mu}-plus-jets final state is analyzed in a data sample of 94 pb{sup -1} and a total of 14 events are selected with a background expectation of 11.7 {+-} 1.9 events. The measurement yields: {sigma}{sub p{bar p} {yields} t{bar t} + X} = 2.4{sub -3.5}{sup +4.2}(stat.){sub -2.6}{sup +2.5}(syst.) {+-} 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in Tevatron Run II data and to measure the production cross section, is combined with results from all available analyses channels. The combined result yields: {sigma}{sub p{bar p}} {yields} t{bar t} + X = 8.1{sub -2.0}{sup +2.2}(stat.){sub -1.4}{sup +1.6}(syst.) {+-} 0.8(lumi.) pb.