Download or read book Top Quark Pair Production Cross Section in the Lepton jets Channel Using B tagging at written by and published by . This book was released on 2008 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark pair production cross section measurement in the lepton+jets channel with b-tagging algorithm is described. About 900 pb−1 data collected by the D0 detector at the Fermilab Tevatron are used for this analysis. In this thesis, event selection, background estimation, and cross section calculation are discussed in detail. In addition, calibration of the Luminosity Monitor readout electronics and a new b-tagging algorithm, the SLTNN tagger, are also discussed in this thesis.
Download or read book Top Quark Pair Production Cross Section in the Lepton jets Channel Using B tagging at DO written by Hwidong Yoo and published by . This book was released on 2008 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark pair production cross section measurement in the lepton+jets channel with b-tagging algorithm is described. About 900 pb-1 data collected by the DO detector at the Fermilab Tevatron are used for this analysis. In this thesis, event selection, background estimation, and cross section calculation are discussed in detail. In addition, calibration of the Luminosity Monitor readout electronics and a new b-tagging algorithm, the SLTNN tagger, are also discussed in this thesis.
Download or read book Measurements of the Top Quark Pair Production Cross Section in Lepton Jets Final States Using a Topological Multivariate Technique as Well as Lifetime B Tagging InProton Anti proton Collisions at S 1 2 written by Tobias F. Golling and published by . This book was released on 2005 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two alternative measurements of the t{bar t} production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t{bar t} production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields {sigma}{sub p{bar p} {yields} t{bar t} + x} = 5.13{sub -1.57}{sup +1.76}(stat){sub -1.10}{sup +0.96}(syst) {+-} 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb{sup -1}, and in the combination with the electron+jets channel 226.3 pb{sup -1} {sigma}{sub p{bar p} {yields} t{bar t} + x} = 6.60{sub -1.28}{sup +1.37}(stat){sub -1.11}{sup +1.25}(syst) {+-} 0.43 (lumi) pb. The second measurement presented reconstructs explicitly secondary vertices to d lifetime b-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4 pb{sup -1} and 168.8 pb{sup -1}, respectively: {sigma}{sub p{bar p} {yields} t{bar t} + x} = 8.24{sub -1.25}{sup +1.34}(stat){sub -1.63}{sup +1.89}(syst) {+-} 0.54 (lumi) pb.
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.
Download or read book Measurement of the Top Pair Production Cross Section in the Lepton Jets Channel Using a Jet Flavor Discriminant written by and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a new method to measure the top quark pair production cross section and the background rates with data corresponding to an integrated luminosity of 2.7 fb−1 from p{bar p} collisions at √s = 1.96 TeV collected with the CDF II Detector. We select events with a single electron or muon candidate, missing transverse energy, and at least one b-tagged jet. We perform a simultaneous fit to a jet flavor discriminant across nine samples defined by the number of jets and b-tags. An advantage of this approach is that many systematic uncertainties are measured in situ and inversely scale with integrated luminosity. We measure a top cross section of [sigma]{sub t{bar t}} = 7.64 ± 0.57 (stat + syst) ± 0.45 (luminosity) pb.
Download or read book Measurements of the Top Quark Pair Production Cross Section in Lepton Jets Final States Using a Topological Multivariate Technique as Well as Lifetime B Tagging in Proton Anti proton Collisions at u221A s written by and published by . This book was released on 2005 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two alternative measurements of the t¯t production cross section at √s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t¯t production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields ?p¯p → t¯t + x = 5.13-1.57+1.76(stat)-1.10+0.96(syst) ± 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb-1, and in the combination with the electron+jets channel (226.3 pb-1) ?p¯p → t¯t + x = 6.60-1.28+1.37(stat)-1.11+1.25(syst) ± 0.43 (lumi) pb. The second measurement presented reconstructs explicitly secondary vertices to d lifetime b-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4 pb-1 and 168.8 pb-1, respectively: ?p¯p → t¯t + x = 8.24-1.25+1.34(stat)-1.63+1.89(syst) ± 0.54 (lumi) pb.
Download or read book Measurements of the Top Quark Pair Production Cross Section in Lepton jets Final States Using a Topological Multivariate Technique as Well as Lifetime B tagging in Proton antiproton Collisions at root written by Tobias Golling and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Cross Section of Top Quark Pairs Produced in Association with a Photon in Lepton Jets Events at 8 s written by Nabin Poudyal and published by . This book was released on 2021 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inclusive production cross section of top quark pairs in association with a photon is measured in proton-proton collisions at the LHC with 13 TeV energy using the full RunII data collected by CMS in 2016, 2017, and 2018 with a total corresponding integrated luminosity of 137 fb 8́21 . The relative fraction of ttÎđ events normalized to inclusive tt production is measured. The cross section measurement provides important information about the electromagnetic coupling of the standard model top quark and is sensitive to physics beyond the standard model. The analysis is carried out in the in semileptonic decay channel with a well isolated high P T lepton (electron and muon), at least four jets out of which at least one must be b-tagged, and an isolated photon. Photons may be emitted from initial state radiation, top quarks, and decay products of top quarks. A simultaneous likelihood fit of control regions with the signal region is done to constraint the backgrounds and to extract the ttÎđ cross section. The measurement of the ratio of ttÎđ to tt is 0.02055 ℗ł 0.00099 (syst.) ℗ł 0.00099 (stat.) in the e + jets channel, 0.02156 ℗ł 0.00068 (syst.) ℗ł 0.00068 (stat.) in ℗æ + jets channel, and 0.02203 ℗ł 0.00064 (syst.) ℗ł 0.00064 (stat.) in the l + jets channel. The measured inclusive cross section is 3.81 ℗ł 0.15 (syst.) ℗ł 0.10 (stat.) pb in e + jets channel, 3.87 ℗ł 0.11 (syst.) ℗ł 0.07 (stat.) pb in ℗æ + jets channel, and 3.96 ℗ł 0.10 (syst.) ℗ł 0.06 (stat.) pb in l + jets channel for full RunII data. The results are in agreement with the standard model next to leading order prediction.
Download or read book Measurements of the Top Quark Pair Production Cross Section in Lepton Jets Final States Using a Topological Multivariate Technique as Well as Lifetime B Tagging in Proton Anti proton Collisions at S 1 2 written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract Not Provided.
Download or read book Measurement of the Top Quark Pair Production Cross Section in the Dilepton Channel Using Lepton Plus Track Selection and Identified B Jets written by and published by . This book was released on 2008 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using 1.0 fb-1 of data collected by the collider detector at fermilab (CDF) from run II of the fermilab tevatron, we measure the t$\bar{t}$ production cross-section in events with two leptons, significant missing transverse energy, and ≥ 2 jets, at least one of which is identified as a b-jet.
Download or read book Measurements of the Top Quark Pair Production Cross Section and Branching Ratio to a W boson and Bottom Quark Using the Semi leptonic and Dilepton Final States with the ATLAS Detector at the LHC written by Robert E. Calkins and published by . This book was released on 2012 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : In the Standard Model, the top quark plays a unique role as the heaviest known fundamental particle and as a quark that decays before it is able to hadronize. Top quarks are expected to decay to a W-boson and a b-quark nearly 100% of the time. If the branching ratio of t → Wb is lower than one, the distribution of the number of b-tagged jets will shift to lower multiplicities. A simultaneous likelihood fit to the number of b-tagged jets distributions in the lepton+jets and dilepton channels is performed on 4.7 fb−1 of data collected by the ATLAS detector to extract both the branching ratio and the tt ̄ cross section. The branching ratio of t → Wb, R, is measured to be 1.06±0.11, which is consistent with the Standard Model value. This is the first measurement of the t → Wb branching ratio performed with the ATLAS detector using both the lepton+jets and dilepton channels at the LHC. The tt ̄ cross section is measured to be [special characters omitted] pb, which agrees with NNLO predictions.
Download or read book Measurement of the Top Quark Pair Production Cross Section in the Dilepton Channel Using Lepton Plus Track Selection and Identified B jets written by Teresa Spreitzer and published by . This book was released on 2008 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using 1.0 fb-1 of data collected by the Collider Detector at Fermilab (CDF) from Run II of the Fermilab Tevatron, we measure the tt ̄ production cross-section in events with two leptons, significant missing transverse energy, and ≥ 2 jets, at least one of which is identified as a b-jet. As the Run II dataset grows, more stringent tests of Standard Model predictions for the top quark sector are becoming possible. The dilepton channel, where both top quarks decay t → Wb → ℓvb, is of particular interest due to its high purity. Use of an isolated Crack as the second lepton significantly increases the dilepton acceptance, at the price of some increase in background, particularly from W + jets events where one of the jets is identified as a lepton. To control the increase in background we add to the event selection the requirement that at least one of the jets be identified as a b-jet, reducing the background contribution from all sources. Assuming a branching ratio of BR(W → ℓ v) = 10.8 % and a top mass of mt = 175 GeV/c2 , the measured cross-section is sigma(pp → tt) = 10.5 +/- 1.8 (stat.) +/- 0.8 (syst. ) +/- 0.6 (lumi.) pb.
Download or read book Discovery of Single Top Quark Production written by Dag Gillberg and published by Springer Science & Business Media. This book was released on 2011-01-22 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking—the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. It documents one of the flagship measurements of the D0 experiment, a collaboration of more than 600 physicists from around the world. It describes first observation of a physical process known as “single top quark production”, which had been sought for more than 10 years before its eventual discovery in 2009. Further, his thesis describes, in detail, the innovative approach Dr. Gillberg took to this analysis. Through the use of Boosted Decision Trees, a machine-learning technique, he observed the tiny single top signal within an otherwise overwhelming background. This Doctoral Thesis has been accepted by Simon Fraser University, Burnaby, BC, Canada.
Download or read book Measurements of the Top Quark Pair Production Cross Section in Lepton jets Final States Using a Topological Multivariate Technique as Well as Lifetime B tagging in Proton antiproton Collisions at s written by Tobias Golling and published by . This book was released on 2005 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Top Quark Pair Production Cross Section and an In situ B tagging Efficiency Calibration with ATLAS in Pp Collisions at s written by Bin Guo and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Identification of Top Quark Production Using Kinematic and B tagging Techniques in the Lepton Jets Channel in Pp Collisions at square Root S written by Gareth M. Houk and published by . This book was released on 1996 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
