First Measurement Of The Top Quark Pair Production Cross Section In Proton Proton Collisions At The Center Of Mass Energy Of 7 Tev
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| Author | : Puneeth D. Kalavase |
| Publisher | : |
| Total Pages | : 167 |
| Release | : 2011 |
| Genre | : |
| ISBN | : 9781124885476 |
The first measurement of the cross section for top-quark pair production in proton-proton collisions at the Large Hadron Collider at center-of-mass energy of 7 TeV has been performed using a data sample corresponding to an integrated luminosity of 3 pb-1 recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1+/-1.0 events expected from background. The measured cross section is 194+/-72 (statistical) +/-24 (systematic) +/-21 (luminosity) pb. The result is consistent with next-to-leading order theoretical predictions.
| Author | : |
| Publisher | : |
| Total Pages | : 26 |
| Release | : 2011 |
| Genre | : |
| ISBN | : |
The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\pm} 1.0 events expected from background. The measured cross section is 194 {\pm} 72 (stat.) {\pm} 24 (syst.) {\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.
| Author | : Anna Christine Henrichs |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 231 |
| Release | : 2013-10-04 |
| Genre | : Science |
| ISBN | : 3319014870 |
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 | : Jan Kieseler |
| Publisher | : Springer |
| Total Pages | : 172 |
| Release | : 2016-06-15 |
| Genre | : Science |
| ISBN | : 3319400053 |
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 | : Geng-Yuan Jeng |
| Publisher | : |
| Total Pages | : 140 |
| Release | : 2011 |
| Genre | : Large Hadron Collider (France and Switzerland) |
| ISBN | : 9781124771243 |
We perform a measurement of the top quark pair production cross section in pp collisions at a center-of-mass energy of 7 TeV at the Large Hadron Collider. The analysis is based on a 36 pb -1 dataset collected with the CMS experiment in 2010. We study the kinematic characteristics of events with exactly one isolated muon in association with additional hard jets and exhibiting substantial missing transverse energy to distinguish the tt− signal from the electroweak and QCD multijet backgrounds. The tt− signal is extracted by simultaneously fitting the tri-jet invariant mass distributions in events with exactly three jets and at least four jets. The measured cross section is 157 ± 12(stat.[Special characters omitted.] (syst.) ± 6(lumi.) pb, which is consistent with the theoretical predictions.
| Author | : Universitat de València. Facultat de Física |
| Publisher | : |
| Total Pages | : 184 |
| Release | : 2014 |
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| ISBN | : |
| Author | : Bin Guo |
| Publisher | : |
| Total Pages | : 234 |
| Release | : 2011 |
| Genre | : |
| ISBN | : 9780494782064 |
We present a measurement of the top anti-top quark (tt ̄ ) 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 tt ̄ 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 tt ̄ cross section is 176+22-21stat. +20-20 (syst.) +/- 6 (lum.) pb in the dilepton channel. We will also discuss the future prospects of this measurement.
| Author | : |
| Publisher | : |
| Total Pages | : 31 |
| Release | : 2012 |
| Genre | : |
| ISBN | : |
The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t anti-t to (l nu(l)) (tau nu(tau)) b anti-b, where l can be either an electron or a muon. The data sample corresponds to an integrated luminosity of 2.0 inverse femtobarns for the electron channel and 2.2 inverse femtobarns for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t anti-t cross section explicitly including tau leptons in proton-proton collisions at sqrt(s)=7 TeV. The measured value sigma(t anti-t) = 143 +/- 14 (stat.) +/- 22 (syst.) +/- 3 (lumi.) pb is consistent with the standard model predictions.
| Author | : |
| Publisher | : |
| Total Pages | : 22 |
| Release | : 2014 |
| Genre | : |
| ISBN | : |
The inclusive cross section for top-quark pair production measured by the CMS experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at next-to-next-to-leading order with various parton distribution functions to determine the top-quark pole mass, $m_t^{pole}$, or the strong coupling constant, $\alpha_S$. With the parton distribution function set NNPDF2.3, a pole mass of 176.7$^{+3.0}_{-2.8}$ GeV is obtained when constraining $\alpha_S$ at the scale of the Z boson mass, $m_Z$, to the current world average. Alternatively, by constraining $m_t^{pole}$ to the latest average from direct mass measurements, a value of $\alpha_S(m_Z)$ = 0.1151$^{+0.0028}_{-0.0027}$ is extracted. This is the first determination of $\alpha_S$ using events from top-quark production.
| Author | : |
| Publisher | : |
| Total Pages | : 48 |
| Release | : 1949 |
| Genre | : |
| ISBN | : |
