Download or read book Search for Additional Higgs Bosons Decaying to Tau Leptons and Measurement of the CP Properties of the Higgs Yukawa Coupling to Top Quarks Using the CMS Detector written by Daniel Winterbottom and published by . This book was released on 2019 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 Nature. This book was released on 2022-02-09 with total page 291 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 Measurement of the Higgs Boson Properties Using Its Decay to a Pair of tau Leptons in Proton proton Collisions at s written by Doyeong Kim and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Compact Muon Solenoid (CMS) detector has successfully operated with the Large Hadron Collider (LHC) collisions since 2010, leading to the Higgs boson discovery in 2012 by the CMS and ATLAS collaborations. The analyses of data taken during Run 2 (2016-2018) has already led to many interesting results about the properties of the Higgs boson and for the most part they are compatible in the context of the standard model (SM) so far. These studies are important because the SM appears to be an approximation of a more general theory. Precise studies of the Higgs boson's interactions with the known matter and force particles are essential to reveal the microscopic deviations from the SM prediction. One of such interactions is Yukawa couplings of the Higgs boson and fermions. The H → [tau tau] decay is the most sensitive fermionic decay mode that allows direct probing of this interaction. This thesis presents a study of the Higgs boson properties by observing its decay to a pair of tau leptons and testing evidence of non-SM interactions in the Higgs boson production. The results exploit the data collected by the CMS detector during LHC Run-2, in proton-proton collisions with a center-of-mass energy of 13 TeV. Firstly, the Higgs bosons' properties were explored by two complementary approaches by measuring its cross sections. Thanks to the observation of the H → [tau tau] decay in 2016, we can measure the total cross section with higher precision. Furthermore, in the first analysis, the cross sections of different Higgs productions were scrutinized using fine selections within each Higgs production mode which are mutually exclusive using the Simplified Template Cross Section (STXS) framework, proposed by the LHC Higgs Cross Section Working Group. In the second analysis, the first-ever measurement of the inclusive and differential fiducial cross sections for the Higgs boson production decaying to a pair of tau leptons was presented. In the third analysis, a search for anomalous couplings in the Higgs production vertex, including Charge-Parity (CP) violating couplings, is also performed targeting Higgs boson production via gluon fusion in association with two jets and vector boson fusion. None of these analyses has found any hint of new physics beyond the SM, but stringent limits on anomalous Higgs boson couplings to data were set and cross sections of the Higgs bosons in smaller phase spaces were precisely measured.
Download or read book Measurements of the CP Properties of the Higgs Boson Couplings to Tau Leptons and Top Quarks with the CMS Experiment written by Albert Kenneth Dow and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The God Particle written by Leon M. Lederman and published by Houghton Mifflin Harcourt. This book was released on 2006 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fascinating tour of particle physics from Nobel Prize winner Leon Lederman. At the root of particle physics is an invincible sense of curiosity. Leon Lederman embraces this spirit of inquiry as he moves from the Greeks' earliest scientific observations to Einstein and beyond to chart this unique arm of scientific study. His survey concludes with the Higgs boson, nicknamed the God Particle, which scientists hypothesize will help unlock the last secrets of the subatomic universe, quarks and all--it's the dogged pursuit of this almost mystical entity that inspires Lederman's witty and accessible history.
Download or read book A Study of the Standard Model Higgs Boson Decaying to a Pair of Tau Leptons with the CMS Detector at the LHC written by Tyler Henry Ruggles and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a 5.5 standard deviation observation of the Higgs boson decaying to fermions using the data collected at the LHC at 13 TeV center-of-mass energy. The studied dataset corresponds to an integrated luminosity of 35.9 inverse femtobarns. The best fit signal strength for the H to tau tau process is measured to be mu = 1.24 ^{+0.29}/{-0.27}, consistent with standard model predictions. Unique event categories are used targeting the leading Higgs boson production processes, gluon fusion, vector boson fusion, and associated production. This provides signal regions sensitive to Higgs boson couplings to both fermions and vector bosons. These two Higgs boson couplings are measured and are consistent with standard model predictions within one standard deviation. This 5.5 standard deviation observation of the H to tau tau process and the consistency of the Higgs boson couplings with the standard model provide confirmation of the Higgs boson Yukawa couplings to fermions. This is evidence that the Higgs field provides mass for the tau lepton in addition to the vector bosons.
Download or read book Particle Physics Reference Library written by Herwig Schopper and published by Springer Nature. This book was released on 2020 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
Download or read book Lectures on LHC Physics written by Tilman Plehn and published by Springer. This book was released on 2014-08-05 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the discovery of the Higgs boson, the LHC experiments have closed the most important gap in our understanding of fundamental interactions, confirming that such interactions between elementary particles can be described by quantum field theory, more specifically by a renormalizable gauge theory. This theory is a priori valid for arbitrarily high energy scales and does not require an ultraviolet completion. Yet, when trying to apply the concrete knowledge of quantum field theory to actual LHC physics - in particular to the Higgs sector and certain regimes of QCD - one inevitably encounters an intricate maze of phenomenological know-how, common lore and other, often historically developed intuitions about what works and what doesn’t. These lectures cover three aspects to help understand LHC results in the Higgs sector and in searches for physics beyond the Standard Model: they discuss the many facets of Higgs physics, which is at the core of this significantly expanded second edition; then QCD, to the degree relevant for LHC measurements; as well as further standard phenomenological background knowledge. They are intended to serve as a brief but sufficiently detailed primer on LHC physics to enable graduate students and all newcomers to the field to find their way through the more advanced literature, and to help those starting to work in this very timely and exciting field of research. Advanced readers will benefit from this course-based text for their own lectures and seminars. .
Download or read book Discovery Of The Higgs Boson written by Aleandro Nisati and published by World Scientific. This book was released on 2016-08-26 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent observation of the Higgs boson has been hailed as the scientific discovery of the century and led to the 2013 Nobel Prize in physics. This book describes the detailed science behind the decades-long search for this elusive particle at the Large Electron Positron Collider at CERN and at the Tevatron at Fermilab and its subsequent discovery and characterization at the Large Hadron Collider at CERN. Written by physicists who played leading roles in this epic search and discovery, this book is an authoritative and pedagogical exposition of the portrait of the Higgs boson that has emerged from a large number of experimental measurements. As the first of its kind, this book should be of interest to graduate students and researchers in particle physics.
Download or read book Measuring the CP Nature of the Yukawa Coupling Between the Higgs Boson and Tau Leptons written by Mohammad Hassan Hassanshahi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Higgs Boson Decays into a Pair of Bottom Quarks written by Cecilia Tosciri and published by Springer Nature. This book was released on 2021-10-22 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the Higgs boson at the Large Hadron Collider (LHC) represents a milestone for the Standard Model (SM) of particle physics. Most of the SM Higgs production and decay rates have been measured at the LHC with increased precision. However, despite its experimental success, the SM is known to be only an effective manifestation of a more fundamental description of nature. The scientific research at the LHC is strongly focused on extending the SM by searching, directly or indirectly, for indications of New Physics. The extensive physics program requires increasingly advanced computational and algorithmic techniques. In the last decades, Machine Learning (ML) methods have made a prominent appearance in the field of particle physics, and promise to address many challenges faced by the LHC. This thesis presents the analysis that led to the observation of the SM Higgs boson decay into pairs of bottom quarks. The analysis exploits the production of a Higgs boson associated with a vector boson whose signatures enable efficient triggering and powerful background reduction. The main strategy to maximise the signal sensitivity is based on a multivariate approach. The analysis is performed on a dataset corresponding to a luminosity of 79.8/fb collected by the ATLAS experiment during Run-2 at a centre-of-mass energy of 13 TeV. An excess of events over the expected background is found with an observed (expected) significance of 4.9 (4.3) standard deviation. A combination with results from other \Hbb searches provides an observed (expected) significance of 5.4 (5.5). The corresponding ratio between the signal yield and the SM expectation is 1.01 +- 0.12 (stat.)+ 0.16-0.15(syst.). The 'observation' analysis was further extended to provide a finer interpretation of the V H(H → bb) signal measurement. The cross sections for the VH production times the H → bb branching ratio have been measured in exclusive regions of phase space. These measurements are used to search for possible deviations from the SM with an effective field theory approach, based on anomalous couplings of the Higgs boson. The results of the cross-section measurements, as well as the constraining of the operators that affect the couplings of the Higgs boson to the vector boson and the bottom quarks, have been documented and discussed in this thesis. This thesis also describes a novel technique for the fast simulation of the forward calorimeter response, based on similarity search methods. Such techniques constitute a branch of ML and include clustering and indexing methods that enable quick and efficient searches for vectors similar to each other. The new simulation approach provides optimal results in terms of detector resolution response and reduces the computational requirements of a standard particles simulation.
Download or read book Measuring the CP Properties of the Higgs Boson in Its Decay to Leptons with the ATLAS Detector written by Sebastiano Spinali and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evidence for the Higgs Boson Yukawa Coupling to Tau Leptons with the ATLAS Detector written by C. Jeske and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evidence for the Higgs boson Yukawa Coupling to Tau Leptons with the ATLAS Detector written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for Displaced Leptons in the ATLAS Detector written by Lesya Horyn and published by Springer Nature. This book was released on 2022-02-07 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).
Download or read book Tau Lepton Reconstruction and Search for Higgs Bosons Decaying to Tau Pairs in the CMS Experiment at the LHC written by Ivo Nicolas Naranjo Fong and published by . This book was released on 2014 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Higgs Bosons Decaying to Aa in the mu mu tau tau Final State in Pp Collisions at arrow written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the decay to a pair of new particles of either the 125 GeV Higgs boson (h) or a second charge parity (CP)-even Higgs boson (H) is presented. The data set corresponds to an integrated luminosity of 20.3 fb-1 of pp collisions at [arrow]" = 8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (a). One of the two a bosons is required to decay to two muons while the other is required to decay to two [tau] leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 to 50 GeV. The upper limits are placed on the production of h 2!aa relative to the standard model gg 2!h production, assuming no coupling of the a boson to quarks. The most stringent limit is placed at 3.5% for ma = 3.75 GeV. Upper limits are also placed on the production cross section of H 2!aa from 2.33 to 0.72 pb, for fixed ma = 5 GeV with mH ranging from 100 to 500 GeV.
