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Author : Markus Seidel
Publisher :
ISBN 13 :
Total Pages : 203 pages
Book Rating : 4.:/5 (923 download)
Download or read book Precise Measurement of the Top-quark Mass at the CMS Experiment Using the Ideogram Method written by Markus Seidel and published by . This book was released on 2015 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 130 pages
Book Rating : 4.:/5 (958 download)
Download or read book A Measurement of the Mass of the Top Quark Using the Ideogram Technique written by and published by . This book was released on 2009 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a measurement of the mass of the top quark on data collected with the D0 detector at the Tevatron collider in the period from 2002 until 2006. The first chapter describes the Standard Model and the prominent role of the top quark mass. The second chapter gives a description of the D0 detector which is used for this measurement. After the p$\bar{p}$ collisions have been recorded, reconstruction of physics objects is required, which is described in Chapter 3. Chapter 4 describes how the interesting collisions in which top quarks are produced are separated from the `uninteresting' ones with a set of selection criteria. The method to extract the top quark mass from the sample of selected collisions (also called events), which is based on the ideogram technique, is explained in Chapter 5, followed in Chapter 6 by the description of the calibration of the method using simulation of our most precise knowledge of nature. Chapter 7 shows the result of the measurement together with some cross checks and an estimation of the uncertainty on this measurement. This thesis concludes with a constraint on the Higgs boson mass.
Author : Jan Kieseler
Publisher : Springer
ISBN 13 : 3319400053
Total Pages : 172 pages
Book Rating : 4.3/5 (194 download)
Download or read book Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass written by Jan Kieseler and published by Springer. This book was released on 2016-06-15 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the first experimental calibration of the top-quark Monte-Carlo mass. It also provides the top-quark mass-independent and most precise top-quark pair production cross-section measurement to date. The most precise measurements of the top-quark mass obtain the top-quark mass parameter (Monte-Carlo mass) used in simulations, which are partially based on heuristic models. Its interpretation in terms of mass parameters used in theoretical calculations, e.g. a running or a pole mass, has been a long-standing open problem with far-reaching implications beyond particle physics, even affecting conclusions on the stability of the vacuum state of our universe. In this thesis, this problem is solved experimentally in three steps using data obtained with the compact muon solenoid (CMS) detector. The most precise top-quark pair production cross-section measurements to date are performed. The Monte-Carlo mass is determined and a new method for extracting the top-quark mass from theoretical calculations is presented. Lastly, the top-quark production cross-sections are obtained – for the first time – without residual dependence on the top-quark mass, are interpreted using theoretical calculations to determine the top-quark running- and pole mass with unprecedented precision, and are fully consistently compared with the simultaneously obtained top-quark Monte-Carlo mass.
Author : Alexander Grohsjean
Publisher : Springer Science & Business Media
ISBN 13 : 364214070X
Total Pages : 155 pages
Book Rating : 4.6/5 (421 download)
Download or read book Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method written by Alexander Grohsjean and published by Springer Science & Business Media. This book was released on 2010-10-01 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main pacemakers of scienti?c research are curiosity, ingenuity, and a pinch of persistence. Equipped with these characteristics a young researcher will be s- cessful in pushing scienti?c discoveries. And there is still a lot to discover and to understand. In the course of understanding the origin and structure of matter it is now known that all matter is made up of six types of quarks. Each of these carry a different mass. But neither are the particular mass values understood nor is it known why elementary particles carry mass at all. One could perhaps accept some small generic mass value for every quark, but nature has decided differently. Two quarks are extremely light, three more have a somewhat typical mass value, but one quark is extremely massive. It is the top quark, the heaviest quark and even the heaviest elementary particle that we know, carrying a mass as large as the mass of three iron nuclei. Even though there exists no explanation of why different particle types carry certain masses, the internal consistency of the currently best theory—the standard model of particle physics—yields a relation between the masses of the top quark, the so-called W boson, and the yet unobserved Higgs particle. Therefore, when one assumes validity of the model, it is even possible to take precise measurements of the top quark mass to predict the mass of the Higgs (and potentially other yet unobserved) particles.
Author : Matteo M. Defranchis
Publisher : Springer Nature
ISBN 13 : 3030903761
Total Pages : 170 pages
Book Rating : 4.0/5 (39 download)
Download or read book First Measurement of the Running of the Top Quark Mass written by Matteo M. Defranchis and published by Springer Nature. This book was released on 2022-01-03 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the first measurement of the running of the top quark mass is presented. This is a fundamental quantum effect that had never been studied before. Any deviation from the expected behaviour can be interpreted as a hint of the presence of physics beyond the Standard Model. All relevant aspects of the analysis are extensively described and documented. This thesis also describes a simultaneous measurement of the inclusive top quark-antiquark production cross section and the top quark mass in the simulation. The measured cross section is also used to precisely determine the values of the top quark mass and the strong coupling constant by comparing to state-of-the-art theoretical predictions. All the theoretical and experimental aspects relevant to the results presented in this thesis are discussed in the initial chapters in a concise but complete way, which makes the material accessible to a wider audience.
Author : Markus Seidel
Publisher :
ISBN 13 :
Total Pages : 79 pages
Book Rating : 4.:/5 (838 download)
Download or read book Measurement If Top Quark Mass and Jet Energy Scale at the CMS Experiment Using the Ideogram Method written by Markus Seidel and published by . This book was released on 2011 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Anna Christine Henrichs
Publisher : Springer Science & Business Media
ISBN 13 : 3319014870
Total Pages : 231 pages
Book Rating : 4.3/5 (19 download)
Download or read book Top Quark Pair Production written by Anna Christine Henrichs and published by Springer Science & Business Media. This book was released on 2013-10-04 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Before any kind of new physics discovery could be made at the LHC, a precise understanding and measurement of the Standard Model of particle physics' processes was necessary. The book provides an introduction to top quark production in the context of the Standard Model and presents two such precise measurements of the production of top quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV that were observed with the ATLAS Experiment at the LHC. The presented measurements focus on events with one charged lepton, missing transverse energy and jets. Using novel and advanced analysis techniques as well as a good understanding of the detector, they constitute the most precise measurements of the quantity at that time.
Author : Kevin Matthew Black
Publisher :
ISBN 13 :
Total Pages : 226 pages
Book Rating : 4.:/5 (316 download)
Download or read book A Precision Measurement of the Top Quark Mass written by Kevin Matthew Black and published by . This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the measurement of the top quark mass using events recorded during a {approx} 230 pb{sup -1} exposure of the D0 detector to proton-anti-proton (p{bar p}) collisions at a center of mass energy of 1.96 TeV. The Standard Model of particle physics predicts that the top quark will decay into a bottom quark and a W boson close to 100% of the time. The bottom quark will hadronize (bind with another quark) and produce a jet of hadronic particles. The W bosons can decay either into a charged lepton and a neutrino or a pair of quarks. this dissertation focuses on the top quark (t{bar t}) events in which one W decays hadronically and the other decays leptonically. Two methods of identifying t{bar t} events from the large number of events produced are used. The first is based on the unique topology of the final state particles of a heavy particle. By using the topological information of the event, the t{bar t} events can be efficiently extracted from the background. The second method relies on the identification of the remnants of the long lived bottom quarks that are expected to be produced in the decay of almost every top quark. Because the largest background processes do not contain bottom quarks, this is an extremely efficient way to select the events retaining about 60% of the t{bar t} events and removing almost 90% of the background. A kinematic fit to the top quark mass is performed on the t{bar t} candidate events using the final state particles that are seen in the detector. A likelihood technique is then used to extract the most likely value of the top quark mass, m{sub t}, and signal fraction. The result for the topological selection is m{sub t} = 169.9 {+-} 5.8(statistical){sub -7.8}{sup +8.0}(systematic) GeV while the results on the sample selected from identification of a b quark in the event is m{sub t} = 170.6 {+-} 4.2(statistical){sub -6.8}{sup +6.3}(systematic) GeV.
Author :
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (873 download)
Download or read book Precision Measurements of the Top Quark Mass and Width with the D0 Detector written by and published by . This book was released on 2010 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of the top quark in 1995 at the Fermliab Tevatron Collider, top quark properties have been measured with ever higher precision. In this article, recent measurements of the top quark mass and its width using up to 3.6 fb−1 of D0 data are summarized. Different techniques and final states have been examined and no deviations within these measurements have been observed. In addition to the direct measurements, a measurement of the top quark mass from its production cross section and a measurement of the top-antitop quark mass difference are discussed. With a mass of 173.3 ± 1.1 GeV, the top quark is the heaviest of all known fundamental particles. Due to the high mass, its Yukawa coupling is close to unity suggesting that it may play a special role in electroweak symmetry breaking. Precise measurements of both, the W boson and the top quark mass, constrain the mass of the yet unobserved Higgs boson and allow to restrict certain extensions of the Standard Model. At the Tevatron collider with a center-of-mass energy of 1.96 TeV, 85% of the top quark pairs are produced in quark-antiquark annihilation; 15% originate from gluon fusion. Top quarks are predicted to decay almost exclusively to a W boson and a bottom quark. According to the number of hadronic W decays, top events are classified into all-jets, lepton+jets and dilepton events. The lepton+jets channel is characterized by four jets, one isolated, energetic charged lepton and missing transverse energy. With 30%, the branching fraction of the lepton+jets channel is about seven times larger than the one of the dilepton channel whereas the signal to background ratio is about three times smaller. The main background in this final state comes from W +jets events. Instrumental background arises from events in which a jet is misidentified as an electron and events with heavy hadrons that decay into leptons which pass the isolation requirements. The topology of the dilepton channel is described by two jets, two isolated, energetic charged leptons and significant missing transverse energy from the undetected neutrinos. The main background are Z + jets and diboson events (WW/WZ/ZZ+jets) as well as instrumental background as characterized above. At the D0 experiment, different techniques are used to measure the top quark mass. They are summarized in the following sections together with the first measurement of the top anti-top quark mass difference and the first precise determination of the top quark width.
Author :
Publisher :
ISBN 13 :
Total Pages : 142 pages
Book Rating : 4.:/5 (953 download)
Download or read book Measurement of the Top Quark Mass in the All Hadronic Final State at the D0 Experiment written by and published by . This book was released on 2013 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest fermion observed to date. A precise measurement of its mass and W boson mass is important to indirect measurements of Higgs boson mass. Furthermore, the top quark mass, W boson mass and Higgs boson mass may test the Standard Model using the correlations between them. Here in this thesis, we present a measurement of the top quark mass in the all hadronic final state using the template method. This final state has the advantage of being fully reconstructed in the detector and having the largest branching fraction. The measurement is performed on 4033 candidate events collected using the DØ detector. The data is collected from pp collisions generated at √s =1.96 GeV by the TEVATRON accelerator, Fermi National Accelerator Laboratory, Batavia IL. This is a two dimensional measurement formulated to extract the top quark mass as well as lower the systematic uncertainty due to the jet energy scale calibration. A kinematic fitter is employed to build the templates of signal and background for various input top quark mass points and jet energy scale variations. These templates are compared to data to obtain the fitted top quark mass, jet energy scale shift and their uncertainties.
Author :
Publisher :
ISBN 13 :
Total Pages : 246 pages
Book Rating : 4.:/5 (873 download)
Download or read book A Precise Measurement of the Top Quark Mass written by and published by . This book was released on 2007 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the mass of the top quark using data from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. Events are selected from the single lepton plus jets final state (t$\bar{t}$ → W+bW-$\bar{b}$ → lvbq$\bar{q}$'$\bar{b}$). The top quark mass is extracted using a calculation of the probability density for a t$\bar{t}$ final state to resemble a data event. This probability density is a function of both top quark mass and energy scale of calorimeter jets, constrained in situ with the hadronic W boson mass. Using 167 events observed in 955 pb-1 integrated luminosity, we achieve the single most precise measurement of top quark mass to date of 170.8 ± 2.2 (stat.) ± 1.4 (syst.) GeV/c2, where the quoted statistical uncertainty includes uncertainty from the determination of the jet energy scale.
Author :
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurements of the Top Quark Mass and Decay Width with the D0 Detector written by and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark discovery in 1995 at Fermilab is one of the major proofs of the standard model (SM). Due to its unique place in SM, the top quark is an important particle for testing the theory and probing for new physics. This article presents most recent measurements of top quark properties from the D0 detector. In particular, the measurement of the top quark mass, the top antitop mass difference and the top quark decay width. The discovery of the top quark in 1995 confirmed the existence of a third generation of quarks predicted in the standard model (SM). Being the heaviest elementary particle known, the top quark appears to become an important particle in our understanding of the standard model and physics beyond it. Because of its large mass the top quark has a very short lifetime, much shorter than the hadronization time. The predicted lifetime is only 3.3 · 10−25s. Top quark is the only quark whose properties can be studied in isolation. A Lorentz-invariant local Quantum Field Theory, the standard model is expected to conserve CP. Due to its unique properties, the top quark provides a perfect test of CPT invariance in the standard model. An ability to look at the quark before being hadronized allows to measure directly mass of the top quark and its antiquark. An observation of a mass difference between particle and antiparticle would indicate violation of CPT invariance. Top quark through its radiative loop correction to the W mass constrains the mass of the Higgs boson. A precise measurement of the top quark mass provides useful information to the search of Higgs boson by constraining its region of possible masses. Another interesting aspect is that the top quark's Yukawa coupling to the Higgs boson is very close to unity (0.996 ± 0.006). That implies it may play a special role in the electroweak symmetry breaking mechanism.
Author :
Publisher :
ISBN 13 :
Total Pages : 153 pages
Book Rating : 4.:/5 (727 download)
Download or read book Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method written by and published by . This book was released on 2008 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark, discovered in 1995 by the CDF and D0 experiments at the Fermilab Tevatron Collider, is the heaviest known fundamental particle. The precise knowledge of its mass yields important constraints on the mass of the yet-unobserved Higgs boson and allows to probe for physics beyond the Standard Model. The first measurement of the top quark mass in the dilepton channel with the Matrix Element method at the D0 experiment is presented. After a short description of the experimental environment and the reconstruction chain from hits in the detector to physical objects, a detailed review of the Matrix Element method is given. The Matrix Element method is based on the likelihood to observe a given event under the assumption of the quantity to be measured, e.g. the mass of the top quark. The method has undergone significant modifications and improvements compared to previous measurements in the lepton+jets channel: the two undetected neutrinos require a new reconstruction scheme for the four-momenta of the final state particles, the small event sample demands the modeling of additional jets in the signal likelihood, and a new likelihood is designed to account for the main source of background containing tauonic Z decay. The Matrix Element method is validated on Monte Carlo simulated events at the generator level. For the measurement, calibration curves are derived from events that are run through the full D0 detector simulation. The analysis makes use of the Run II data set recorded between April 2002 and May 2008 corresponding to an integrated luminosity of 2.8 fb−1. A total of 107 t{bar t} candidate events with one electron and one muon in the final state are selected. Applying the Matrix Element method to this data set, the top quark mass is measured to be m{sub top}{sup Run IIa} = 170.6 ± 6.1(stat.){sub -1.5}{sup +2.1}(syst.)GeV; m{sub top}{sup Run IIb} = 174.1 ± 4.4(stat.){sub -1.8}{sup +2.5}(syst.)GeV; m{sub top}{sup comb} = 172.9 ± 3.6(stat.) ± 2.3(syst.)GeV. Systematic uncertainties are discussed, and the results are interpreted within the Standard Model of particle physics. As the main systematic uncertainty on the top quark mass comes from the knowledge of the absolute jet energy scale, studies for a simultaneous measurement of the top quark mass and the b jet energy scale are presented. The prospects that such a simultaneous determination offer for future measurements of the top quark mass are outlined.
Author : Oleg Brandt
Publisher :
ISBN 13 :
Total Pages : 118 pages
Book Rating : 4.:/5 (316 download)
Download or read book Measurement of the Mass of the Top Quark in Dilepton Final States with the D0 Detector written by Oleg Brandt and published by . This book was released on 2006 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Standard Model (SM) the top quark mass is a fundamental parameter. Its precise measurement is important to test the self-consistency of the SM. Additionally, it offers sensitivity to New Physics beyond the Standard Model. In proton anti-proton collisions at a centre-of-mass energy of {radical}s = 1.96 TeV t{bar t} quarks are pair-produced, each decaying into a W boson and a b quark. In the dilepton channel both W bosons decay leptonically. Because of the presence of two neutrinos in the final state the kinematics are underconstrained. A so-called Neutrino Weighting algorithm is used to calculate a weight for the consistency of a hypothesized top quark mass with the event kinematics. To render the problem solvable, the pseudorapidities of the neutrinos are assumed. The Maximum Method, which takes the maximum to the weight distribution as input to infer the top quark mass, is applied to approximately 370 pb{sup -1} of Run-II data, recorded by the D0 experiment at the Tevatron. The e{mu}-channel of the 835 pb{sup -1} dataset is analyzed.
Download or read book Measurements of the Top Quark Mass with the D0 Detector written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mass of the top quark is a fundamental parameter of the standard model (SM) and has to be determined experimentally. In this talk, I present the most recent measurements of the top quark mass in $p\bar p$ collisions at $\sqrt s=1.96$~TeV recorded by the D0 experiment at the Fermilab Tevatron Collider. The measurements are performed in final states containing two leptons, using 5.4~\fb of integrated luminosity, and one lepton, using 9.7~\fb of integrated luminosity. The latter constitutes the most precise single measurement of the mass of the top quark, corresponding to a relative precision of 0.43\%. I conclude with a combination of our results with the results by the CDF collaboration, attaining a relative precision of 0.37\%.
Author :
Publisher :
ISBN 13 :
Total Pages : 214 pages
Book Rating : 4.:/5 (925 download)
Download or read book A Precise Measurement of the Top Quark Mass in Dilepton Final States Using 9.7 Fb$^{-1}$ of D{\O} Run II Data written by and published by . This book was released on 2015 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is a very special fundamental particle in the Standard Model (SM) mainly due to its heavy mass. The top quark has extremely short lifetime and decays before hadronization. This reduces the complexity for the measurement of its mass. The top quark couples very strongly to the Higgs boson since the fermion-Higgs Yukawa coupling linearly depends on the fermion's mass. Therefore, the top quark is also heavily involved in Higgs production and related study. A precise measurement of the top quark mass is very important, as it allows for self-consistency check of the SM, and also gives a insight about the stability of our universe in the SM context. This dissertation presents my work on the measurement of the top quark mass in dilepton final states of t$\bar{t}$ events in p$\bar{p}$ collisions at √s = 1.96 TeV, using the full DØ Run II data corresponding to an integrated luminosity of 9.7 fb-1 at the Fermilab Tevatron. I extracted the top quark mass by reconstructing event kinematics, and integrating over expected neutrino rapidity distributions to obtain solutions over a scanned range of top quark mass hypotheses. The analysis features a comprehensive optimization that I made to minimize the expected statistical uncertainty. I also improve the calibration of jets in dilepton events by using the calibration determined in t$\bar{t}$ → lepton+jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. The measured mass is 173.11 ± 1.34(stat)+0.83 -0.72(sys) GeV .
Author : Pieter Willem Huib Houben
Publisher :
ISBN 13 : 9789090240763
Total Pages : 130 pages
Book Rating : 4.2/5 (47 download)
Download or read book A Measurement of the Mass of the Top Quark Using the Ideogram Technique written by Pieter Willem Huib Houben and published by . This book was released on 2009 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
