Top Quark Pair Production Cross Sections And Calibration Of The Top Quark Monte Carlo Mass PDF Download
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| Author | : Jan Kieseler |
| Publisher | : Springer |
| Total Pages | : 172 |
| Release | : 2016-06-15 |
| Genre | : Science |
| ISBN | : 3319400053 |
Download Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass Book in PDF, ePub and Kindle
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 | : Jan Kieseler |
| Publisher | : |
| Total Pages | : |
| Release | : 2015 |
| Genre | : |
| ISBN | : |
Download Measurement of Top-quark Pair Production Cross Sections and Calibration of the Top-quark Monte-Carlo Mass Using LHC Run I Proton-proton Collision Data at √s Book in PDF, ePub and Kindle
| Author | : Anna Christine Henrichs |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 231 |
| Release | : 2013-10-04 |
| Genre | : Science |
| ISBN | : 3319014870 |
Download Top Quark Pair Production Book in PDF, ePub and Kindle
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 | : Bin Guo |
| Publisher | : |
| Total Pages | : |
| Release | : 2012 |
| Genre | : |
| ISBN | : |
Download Measurement of the Top Quark Pair Production Cross Section and an In-situ B-tagging Efficiency Calibration with ATLAS in Pp Collisions at √s Book in PDF, ePub and Kindle
We present a measurement of the top anti-top quark (ttbar)production cross section in the dilepton final states from proton-proton collisions at a center of mass energy at 7 TeV at the LHC. A b-tagging algorithm based on tracks displaced from the event interaction vertex is applied to identify bottom quark jets from top quark decay and reject background events. Given the relatively pure sample of bottom quark jets in ttbar dilepton final states, a new technique to measure in-situ the b-tagging efficiency is introduced that uses the distribution of the number of observed b-tagged jets. We present results with data collected at the ATLAS detector in 2010 with an integrated luminosity of 35 pb-1. The measured ttbar cross section is 176 +22/-21 (stat.) ± 20 (syst.) ± 6 (lum.) pb in the dilepton channel. We will also discuss the future prospects of this measurement.
| Author | : Alexander Grohsjean |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 155 |
| Release | : 2010-10-01 |
| Genre | : Science |
| ISBN | : 364214070X |
Download Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method Book in PDF, ePub and Kindle
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 | : |
| Publisher | : |
| Total Pages | : 233 |
| Release | : 2010 |
| Genre | : |
| ISBN | : |
Download Measurement of Cross Section of Quark Pair Production Top with the D0 Experiment at the Tevatron and Determination the Top Quark Mass Using this Measure Book in PDF, ePub and Kindle
The top quark has been discovered by CDF and D0 experiments in 1995 at the proton-antiproton collider Tevatron. The amount of data recorded by both experiments makes it possible to accurately study the properties of this quark: its mass is now known to better than 1% accuracy. This thesis describes the measurement of the top pair cross section in the electron muon channel with 4, 3 fb−1 recorded data between 2006 and 2009 by the D0 experiment. Since the final state included a muon, improvements of some aspects of its identification have been performed : a study of the contamination of the cosmic muons and a study of the quality of the muon tracks. The cross section measurement is in good agreement with the theoretical calculations and the other experimental measurements. This measurement has been used to extract a value for the top quark mass. This method allows for the extraction of a better defined top mass than direct measurements as it depends less on Monte Carlo simulations. The uncertainty on this extracted mass, dominated by the experimental one, is however larger than for direct measurements. In order to decrease this uncertainty, the ratio of the Z boson and the top pair production cross sections has been studied to look for some possible theoretical correlations. At the Tevatron, the two cross sections are not theoretically correlated: no decrease of the uncertainty on the extracted top mass is therefore possible.
| Author | : Jean-François Arguin |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2006 |
| Genre | : |
| ISBN | : 9780494159187 |
Download Measurement of the Top Quark Mass with in Situ Jet Energy Scale Calibration Using Hadronic W Boson Decays at CDF-II. Book in PDF, ePub and Kindle
We report a measurement of the top quark mass with the upgraded Collider Detector at Fermilab (CDF-II). The top quarks are produced in pairs (tt−) in proton-antiproton collisions with a center-of-mass energy of 1.96 TeV. Each top quark decays to a W boson and a bottom quark. We select candidate events in which one W boson decays hadronically and the other decays to an electron or a muon and its associated neutrino. The data sample, which corresponds to an integrated luminosity of 318 pb-1, contains 138 tt− candidates. A top quark mass is reconstructed for each event by placing energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of the hadronic W boson decays W & rarr; jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement, the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain Mtop = 173.5+3.9-3.8 GeV/c2. This constitutes the most precise measurement of the top quark mass to date. This measurement can be used to constrain the mass of the Higgs boson, a central particle in the Standard Model of particle physics that has yet to be observed. We also demonstrate that this new technique reduces naturally the jet, energy scale uncertainty as more data is accumulated and thus provides the capability to measure Mtop with an uncertainty of 2 GeV/c2 or better by the end of the CDF-II experiment.
| Author | : Matteo M. Defranchis |
| Publisher | : Springer Nature |
| Total Pages | : 170 |
| Release | : 2022-01-03 |
| Genre | : Science |
| ISBN | : 3030903761 |
Download First Measurement of the Running of the Top Quark Mass Book in PDF, ePub and Kindle
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 | : Jean-Francois Arguin |
| Publisher | : |
| Total Pages | : 179 |
| Release | : 2005 |
| Genre | : |
| ISBN | : |
Download Measurement of the Top Quark Mass with In Situ Jet Energy Scale Calibration Using Hadronic W Boson Decays at CDF-II. Book in PDF, ePub and Kindle
| Author | : Eike Steffen Schlieckau |
| Publisher | : |
| Total Pages | : 101 |
| Release | : 2014 |
| Genre | : |
| ISBN | : |
Download Measurement of Top-quark Mass and Inclusive Top-quark-pair Production Cross Section in Pp Collisions at √s Book in PDF, ePub and Kindle
