Download or read book A Search for the Standard Model Higgs Boson Produced in Association with Top Quark Pairs in the Leptons Jets Final State at CDF II written by Jake Connors and published by . This book was released on 2011 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In nature we have observed that the weak force is inherently short ranged, and thus must be mediated via heavy gauge bosons. Explicitly adding mass terms for these particles to the Standard Model Lagrangian, however, breaks the gauge symmetry upon which the theory is constructed. In 1964, the so-called "Higgs Mechanism" was independently proposed by Robert Brout, Francois Englert and Peter Higgs, which spontaneously gives rise to the masses of the gauge bosons as well as the fermions. In the Higgs mechanism, a new complex scalar $SU(2)$ doublet field is added to the SM Lagrangian which below a critical temperature acquires a vacuum expectation value through spontaneous electroweak symmetry breaking. When this field is re-expanded around its new minimum, the mediating gauge fields of the electroweak interaction are mixed to produce three heavy gauge bosons $\left(W^+, W^-, Z^0\right)$ and one massless boson, the photon. The quanta of this new field has come to be called the Higgs boson and verifying its existence remains to be one of the last important tests of the Standard Model. The mass of this new particle, however, cannot be directly calculated due to the unknown self-coupling parameter of the Higgs field. Presented within is a search for the SM Higgs boson produced in association with a top quark pair at the CDF II detector at the Tevatron in \SI{6.3}{\per\femto\barn} of data. We consider events which have 1 or more identified charged leptons, an imbalance in transverse momentum and at least 5 jets, where at least two of these jets are consistent with originating from the decay of a $B$ hadron. Using a neural network ensemble technique, we place 95\% confidence level upper limits on the $t\bar{t}H$ production cross section for several Higgs boson masses ranging from \SI{100}{\giga\eV\per c^2} to \SI{150}{\giga\eV\per c^2}. For a mass of \SI{120}{\giga\eV\per c^2} the expected limit is $16.3$ times the standard model predicted cross section.
Download or read book A Search for the Standard Model Higgs Boson Produced in Association with Top Quarks in the Lepton Jets Channel at CMS written by Geoffrey N. Smith and published by . This book was released on 2014 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Flavor Changing Neutral Current Top Quark Decays t Hq with H bb in pp Collisions at s 8 TeV with the ATLAS Detector written by Shota Tsiskaridze and published by Springer. This book was released on 2017-08-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: This PhD thesis focuses on the search for flavor-changing neutral currents in the decay of a top quark to an up-type quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb. Further, the thesis presents the combination of this search for top quark pair events with other ATLAS searches – in the course of which the most restrictive bounds to date on tqH interactions were obtained. Following on from the discovery of the Higgs boson, it is particularly important to measure the Yukawa couplings of the Standard Model fermions; these parameters may provide crucial insights to help solve the flavor puzzle and may help reveal the presence of new physics before it is directly observed in experiments.
Download or read book Search for the Standard Model Higgs Boson Produced in Association with Top Quarks in the Lepton Plus Jets Channel written by Sean C. Flowers and published by . This book was released on 2017 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results for the search of a Higgs boson decaying to a bottom quark-antiquark pair produced with a top quark-antiquark pair (t ̄tH) in the lepton plus jets channel in proton-proton collisions at a center-of-mass energy of √ s = 13 TeV are presented. The data used corresponds to an integrated luminosity of 12.9 fb−1 recorded with the CMS experiment in 2016. To increase the sensitivity of the search, selected events are categorized by number of jets and number of b-tagged jets resulting in different expected signal and background rates. For each category two multivariate techniques are combined to separate the signal and background events. A machine learning process called a boosted decision tree (BDT) is trained on the two types of classes of events and then split into high and low purity based on the output. The physics motivated matrix element method (MEM) is applied to the BDT output to obtain the final two dimensional discriminator. The result is presented in terms of the t ̄tH signal strength modifier μ, the ratio of the observed t ̄tH production cross section relative to the expected cross section based on a 125 GeV Standard Model Higgs boson. A combined fit of the final discriminant in all categories of the lepton plus jets channel results an observed (expected) upper limit of μ
Download or read book High Energy Physics 99 Proceedings of the International Europhysics Conference on High Energy Physics Tampere Finland 15 21 July 1999 written by K Huitu and published by CRC Press. This book was released on 2000-01-01 with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Energy Physics 99 contains the 18 invited plenary presentations and 250 contributions to parallel sessions presented at the International Europhysics Conference on High Energy Physics. The book provides a comprehensive survey of the latest developments in high energy physics. Topics discussed include hard high energy, structure functions, soft interactions, heavy flavor, the standard model, hadron spectroscopy, neutrino masses, particle astrophysics, field theory, and detector development.
Download or read book A Search for the Standard Model Higgs Boson Produced in Association with Top Quarks written by Jonathan S. Wilson and published by . This book was released on 2012 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: We have performed a search for the Standard Model Higgs boson produced in association with top quarks in the lepton plus jets channel. We impose no constraints on the decay of the Higgs boson. We employ ensembles of neural networks to discriminate events containing a Higgs boson from the dominant di-top background, and set upper bounds on the Higgs production cross section. At a Higgs boson mass mH = 120 GeV/c2, we expect to exclude a cross section 12.7 times the Standard Model prediction, and we observe an exclusion 27.4 times the Standard Model prediction with 95% confidence.
Download or read book Search for the Standard Higgs Boson Produced in Association with a Pair of Top Quark in the Multi leptons Channel in the CMS Experiment written by Xavier Coubez and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the last elementary particle predicted by the Standard Model, the Higgs boson, has opened a new era in particle physics. One of the objectives now is to probe the coupling of the Higgs boson to other particles in order to confirm the validity of the model. The work of this thesis focused initially on the identification of jets coming from b quark at trigger level. The goal is to allow for the selection of one thousand events among the forty million produced every second at the LHC, by identifiying objects present in the final states of interesting physics processes such as the associated production of a Higgs boson decaying in a pair of b quark with a Z boson decaying into undetected neutrinos. The work then moved to the study of the coupling of the Higgs boson to the quark top, most massive particle in the Standard Model. After a study of one of the important background of the associated production of the Higgs boson and a top quark pair, a new method called matrix element method has been used to improve the discrimination between signal and background. This analysis has led to the first experimental evidence of coupling between the Higgs boson and the top quark.
Download or read book Perspectives on Higgs Physics II written by G. L. Kane and published by World Scientific. This book was released on 1997 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model of particle physics is extremely successful in describing nature. It is, however, incomplete in one major way: the masses of gauge bosons and fermions enter the Standard Model through the Higgs mechanism. That is completely satisfactory technically, but it is not understood physically. We do not yet know what nature really does to give mass to particles. Understanding Higgs physics is necessary in order to complete the Standard Model, and to learn how to extend it and improve its foundations.This book is a collection of current work and thinking about these questions by active workers. It speculates about what form the answers will take, as well as updates and extends previous books and reviews. Some chapters emphasize theoretical questions, some focus on connections with other areas of physics, and some discuss how we can get data to uncover nature's solution. This second edition adds information and insights from the last five years, including the recent indirect but statistically significant evidence for the existence of a Higgs boson from precision measurements. It contains contributions from Blondel, Quiros, Haber, Pokorski, Dawson, Janot, Mrenna, Gunion, Ibanez, Ross, Bigi, Carena, Wagner, Georgi, Chanowitz, Yuan, Hill, and others.
Download or read book Search for the Higgs Boson in the All Hadronic Final State Using the CDF II Detector written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports the result of a search for the Standard Model Higgs boson in events containing four reconstructed jets associated with quarks. For masses below 135 GeV/c2, the Higgs boson decays to bottom-antibottom quark pairs are dominant and result primarily in two hadronic jets. An additional two jets can be produced in the hadronic decay of a W or Z boson produced in association with the Higgs boson, or from the incoming quarks that produced the Higgs boson through the vector boson fusion process. The search is performed using a sample of s = sqrt(1.96) TeV proton-antiproton collisions corresponding to an integrated luminosity of 9.45 fb-1 recorded by the CDF II detector. The data are in agreement with the background model and 95% credibility level upper limits on Higgs boson production are set as a function of the Higgs boson mass. The median expected (observed) limit for a 125 GeV/c2 Higgs boson is 11.0 (9.0) times the predicted standard model rate.
Download or read book The Standard Model Higgs Boson written by Martin B. Einhorn and published by North Holland. This book was released on 1991 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 8.
Download or read book Search for a Standard Model Higgs Boson Produced in Association with a Top quark Pair and Decaying to Bottom Quarks Using a Matrix Element Method written by and published by . This book was released on 2015 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson Produced in Association with Top Quarks written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Higgs Boson Produced in Association with Top Quarks with the CMS Detector at the LHC written by Cristina Martin Perez and published by Springer. This book was released on 2023-02-10 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.
Download or read book Top Quark Physics at Hadron Colliders written by Arnulf Quadt and published by Springer Science & Business Media. This book was released on 2007-08-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This will be a required acquisition text for academic libraries. More than ten years after its discovery, still relatively little is known about the top quark, the heaviest known elementary particle. This extensive survey summarizes and reviews top-quark physics based on the precision measurements at the Fermilab Tevatron Collider, as well as examining in detail the sensitivity of these experiments to new physics. Finally, the author provides an overview of top quark physics at the Large Hadron Collider.
Download or read book Quark Confinement and the Hadron Spectrum VII written by Jose Emilio F. T. Ribeiro and published by AIP Conference Proceedings (Nu. This book was released on 2007-03-14 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume features papers presented at the 7th Conference on Quark Confinement and the Hadron Spectrum. It covers the up-to-date research done in the physics of quarks and their role as ultimate constituents of matter. It will be of interest to all theoreticians and experimentalists working in these areas.
Download or read book The Standard Theory of Particle Physics written by Luciano Maiani and published by World Scientific Publishing Company. This book was released on 2016-08-25 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a quite complete and up-to-date picture of the Standard Theory with an historical perspective, with a collection of articles written by some of the protagonists of present particle physics. The theoretical developments are described together with the most up-to-date experimental tests, including the discovery of the Higgs Boson and the measurement of its mass as well as the most precise measurements of the top mass, giving the reader a complete description of our present understanding of particle physics.
Download or read book Evidence for a Standard Model Higgs Boson Produced in Association with a Top Quark Pair and Decaying to Leptons written by Charles N. Mueller and published by . This book was released on 2017 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt:
