Search for the Standard Model Higgs Boson in the H → ZZ → l + l - qq Decay Channel at CMS

Search for the Standard Model Higgs Boson in the H → ZZ → l + l - qq Decay Channel at CMS

Author: Francesco Pandolfi

Publisher: Springer Science & Business Media

Published: 2013-08-15

Total Pages: 137

ISBN-13: 3319009036

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The theoretical foundations of the Standard Model of elementary particles relies on the existence of the Higgs boson, a particle which has been revealed for the first time by the experiments run at the Large Hadron Collider (LHC) in 2012. As the Higgs boson is an unstable particle, its search strategies were based on its decay products. In this thesis, Francesco Pandolfi conducted a search for the Higgs boson in the H → ZZ → l + l - qq Decay Channel with 4.6 fb -1 of 7 TeV proton-proton collision data collected by the Compact Muon Solenoid (CMS) experiment. The presence of jets in the final state poses a series of challenges to the experimenter: both from a technical point of view, as jets are complex objects and necessitate of ad-hoc reconstruction techniques, and from an analytical one, as backgrounds with jets are copious at hadron colliders, therefore analyses must obtain high degrees of background rejection in order to achieve competitive sensitivity. This is accomplished by following two directives: the use of an angular likelihood discriminant, capable of discriminating events likely to originate from the decay of a scalar boson from non-resonant backgrounds, and by using jet parton flavor tagging, selecting jets compatible with quark hadronization and discarding jets more likely to be initiated by gluons. The events passing the selection requirements in 4.6 fb -1 of data collected by the CMS detector are examined, in the search of a possible signal compatible with the decay of a heavy Higgs boson. The thesis describes the statistical tools and the results of this analysis. This work is a paradigm for studies of the Higgs boson with final states with jets. The non-expert physicists will enjoy a complete and eminently readable description of a proton-proton collider analysis. At the same time, the expert reader will learn the details of the searches done with jets at CMS.


The Physics of the Quark-Gluon Plasma

The Physics of the Quark-Gluon Plasma

Author: Sourav Sarkar

Publisher: Springer Science & Business Media

Published: 2009-12-16

Total Pages: 374

ISBN-13: 3642022855

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The aim of this book is to offer to the next generation of young researchers a broad and largely self-contained introduction to the physics of heavy ion collisions and the quark-gluon plasma, providing material beyond that normally found in the available textbooks. For each of the main aspects - QCD thermodynamics and global features of the QGP, collision hydrodynamics, electromagnetic probes, jet and quarkonium production, color glass condensate, and the gravity connection - the present volume provides extensive and pedagogical lectures, surveying the present status of both theory and experiment. A particular feature of this volume is that all lectures have been written with the active assistance of selected students present at the course in order to ensure the adequate level and coverage for the intended readership.


Discovery and Measurement of the Higgs Boson in the WW Decay Channel

Discovery and Measurement of the Higgs Boson in the WW Decay Channel

Author: David Hall

Publisher: Springer

Published: 2015-06-15

Total Pages: 175

ISBN-13: 3319199897

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This thesis describes the stand-alone discovery and measurement of the Higgs boson in its decays to two W bosons using the Run-I ATLAS dataset. This is the most precise measurement of gluon-fusion Higgs boson production and is among the most significant results attained at the LHC. The thesis provides an exceptionally clear exposition on a complicated analysis performed by a large team of researchers. Aspects of the analysis performed by the author are explained in detail; these include new methods for evaluating uncertainties on the jet binning used in the analysis and for estimating the background due to associated production of a W boson and an off-shell photon. The thesis also describes a measurement of the WW cross section, an essential background to Higgs boson production. The primary motivation of the LHC was to prove or disprove the existence of the Higgs boson. In 2012, CERN announced this discovery and the resultant ATLAS publication contained three decay channels: gg, ZZ, and WW.


Towards Quantum Gravity

Towards Quantum Gravity

Author: Jerzy Kowalski-Glikman

Publisher: Springer Science & Business Media

Published: 2000-01-24

Total Pages: 387

ISBN-13: 3540669108

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The aim of this book is to give graduate students an overview of quantum gravity but it also covers related topics from astrophysics. Some well-written contributions can serve as an introduction into basic conceptual concepts like time in quantum gravity or the emergence of a classical world from quantum cosmology. This makes the volume attractive to philosophers of science, too. Other topics are black holes, gravitational waves and non-commutative extensions of physical theories.


Frontiers and Challenges in Warm Dense Matter

Frontiers and Challenges in Warm Dense Matter

Author: Frank Graziani

Publisher: Springer Science & Business

Published: 2014-04-28

Total Pages: 294

ISBN-13: 3319049127

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Warm Dense Matter (WDM) occupies a loosely defined region of phase space intermediate between solid, liquid, gas, and plasma, and typically shares characteristics of two or more of these phases. WDM is generally associated with the combination of strongly coupled ions and moderately degenerate electrons, and careful attention to quantum physics and electronic structure is essential. The lack of a small perturbation parameter greatly limits approximate attempts at its accurate description. Since WDM resides at the intersection of solid state and high energy density physics, many high energy density physics (HEDP) experiments pass through this difficult region of phase space. Thus, understanding and modeling WDM is key to the success of experiments on diverse facilities. These include the National Ignition Campaign centered on the National Ignition Facility (NIF), pulsed-power driven experiments on the Z machine, ion-beam-driven WDM experiments on the NDCX-II, and fundamental WDM research at the Linear Coherent Light Source (LCLS). Warm Dense Matter is also ubiquitous in planetary science and astrophysics, particularly with respect to unresolved questions concerning the structure and age of the gas giants, the nature of exosolar planets, and the cosmochronology of white dwarf stars. In this book we explore established and promising approaches to the modeling of WDM, foundational issues concerning the correct theoretical description of WDM, and the challenging practical issues of numerically modeling strongly coupled systems with many degrees of freedom.


Scalar Boson Decays to Tau Leptons

Scalar Boson Decays to Tau Leptons

Author: Cécile Caillol

Publisher: Springer

Published: 2017-11-15

Total Pages: 282

ISBN-13: 3319706500

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This thesis presents a study of the scalar sector in the standard model (SM), as well as various searches for an extended scalar sector in theories beyond the SM (BSM). The first part of the thesis details the search for an SM Higgs boson decaying to taus, and produced by gluon fusion, vector boson fusion, or associated production with a vector boson, leading to evidence for decays of the Higgs boson to taus. In turn, the second part highlights several searches for an extended scalar sector, with scalar boson decays to taus. In all of the analyses presented, at least one scalar boson decays to a pair of taus. The results draw on data collected by the Compact Muon Solenoid (CMS) detector during proton–proton collisions with a center-of-mass energy of 7 or 8 TeV.


Hadronic Structure

Hadronic Structure

Author: José L. Goity

Publisher: World Scientific

Published: 2001

Total Pages: 347

ISBN-13: 981281020X

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This volume contains lectures presented at the 14th Annual Hampton University Graduate Studies at the Continuous Electron Beam Accelerator Facility (HUGS at CEBAF), that took place at Jefferson Lab and Hampton University from June 1st to 18th, 1999. The programme was focused on the structure of hadrons from the low to the high energy regimes, including a balance of theory and experiment, and emphasized topics in electron scattering on the nucleon and nuclei.


Extreme States of Matter

Extreme States of Matter

Author: Vladimir E. Fortov

Publisher: Springer

Published: 2015-12-26

Total Pages: 714

ISBN-13: 3319189530

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With its many beautiful colour pictures, this book gives fascinating insights into the unusual forms and behaviour of matter under extremely high pressures and temperatures. These extreme states are generated, among other things, by strong shock, detonation and electric explosion waves, dense laser beams, electron and ion beams, hypersonic entry of spacecraft into dense atmospheres of planets and in many other situations characterized by extremely high pressures and temperatures. Written by one of the world's foremost experts on the topic, this book will inform and fascinate all scientists dealing with materials properties and physics and also serve as an excellent introduction to plasma-, shock-wave and high-energy-density physics for students and newcomers seeking an overview. This second edition is thoroughly revised and expanded, in particular with new material on high energy-density physics, nuclear explosions and other nuclear transformation processes.