ATLAS Measurements of the Higgs Boson Coupling to the Top Quark in the Higgs to Diphoton Decay Channel
ATLAS Measurements of the Higgs Boson Coupling to the Top Quark in the Higgs to Diphoton Decay Channel

Author: Jennet Elizabeth Dickinson

Publisher: Springer Nature

Published: 2021-11-16

Total Pages: 233

ISBN-13: 3030863689

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During Run 2 of the Large Hadron Collider, the ATLAS experiment recorded proton-proton collision events at 13 TeV, the highest energy ever achieved in a collider. Analysis of this dataset has provided new opportunities for precision measurements of the Higgs boson, including its interaction with the top quark. The Higgs-top coupling can be directly probed through the production of a Higgs boson in association with a top-antitop quark pair (ttH). The Higgs to diphoton decay channel is among the most sensitive for ttH measurements due to the excellent diphoton mass resolution of the ATLAS detector and the clean signature of this decay. Event selection criteria were developed using novel Machine Learning techniques to target ttH events, yielding a precise measurement of the ttH cross section in the diphoton channel and a 6.3 $\sigma$ observation of the ttH process in combination with other decay channels, as well as stringent limits on CP violation in the Higgs-top coupling.

Electroweak Physics at the LHC
Electroweak Physics at the LHC

Author: Matthias U. Mozer

Publisher: Springer

Published: 2016-03-24

Total Pages: 121

ISBN-13: 3319303813

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The book discusses the recent experimental results obtained at the LHC that involve electroweak bosons. The results are placed into an appropriate theoretical and historical context. The work pays special attention to the rising subject of hadronically decaying bosons with high boosts, documenting the state-of-the-art identification techniques and highlighting typical results. The text is not limited to electroweak physics in the strict sense, but also discusses the use of electroweak vector-bosons as tool in the study of other subjects in particle physics, such as determinations of the proton structure or the search for new exotic particles. The book is particularly well suited for graduate students, starting their thesis work on topics that involve electroweak bosons, as the book provides a comprehensive description of phenomena observable at current accelerators as well as a summary of the most relevant experimental techniques.

QCD Radiation in Top-Antitop and Z+Jets Final States
QCD Radiation in Top-Antitop and Z+Jets Final States

Author: Kiran Joshi

Publisher: Springer

Published: 2015-06-12

Total Pages: 188

ISBN-13: 3319196537

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This thesis contains new research in both experimental and theoretical particle physics, making important contributions in each. Two analyses of collision data from the ATLAS experiment at the LHC are presented, as well as two phenomenological studies of heavy coloured resonances that could be produced at the LHC. The first data analysis was the measurement of top quark-antiquark production with a veto on additional jet activity. As the first detector-corrected measurement of jet activity in top-antitop events it played an important role in constraining the theoretical modelling, and ultimately reduced these uncertainties for ATLAS's other top-quark measurements by a factor of two. The second data analysis was the measurement of Z+2jet production and the observation of the electroweak vector boson fusion (VBF) component. As the first observation of VBF at a hadron collider, this measurement demonstrated new techniques to reliably extract VBF processes and paved the way for future VBF Higgs measurements. The first phenomenological study developed a new technique for identifying the colour of heavy resonances produced in proton-proton collisions. As a by-product of this study an unexpected and previously unnoticed correlation was discovered between the probability of correctly identifying a high-energy top and the colour structure of the event it was produced in. The second phenomenological study explored this relationship in more detail, and could have important consequences for the identification of new particles that decay to top quarks.

The Black Book of Quantum Chromodynamics
The Black Book of Quantum Chromodynamics

Author: John Campbell

Publisher: Oxford University Press

Published: 2018

Total Pages: 760

ISBN-13: 0199652740

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This title provides an in-depth introduction to the particle physics of current and future experiments at particle accelerators. The text provides the reader with an overview of practically all aspects of the strong interaction necessary to understand and appreciate modern particle phenomenology at the energy frontier.

Search for Supersymmetry in Hadronic Final States
Search for Supersymmetry in Hadronic Final States

Author: Hannsjörg Artur Weber

Publisher: Springer

Published: 2015-06-11

Total Pages: 217

ISBN-13: 3319199560

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The project reported here was a search for new super symmetric particles in proton-proton collisions at the LHC. It has produced some of the world’s best exclusion limits on such new particles. Furthermore, dedicated simulation studies and data analyses have also yielded essential input to the upgrade activities of the CMS collaboration, both for the Phase-1 pixel detector upgrade and for the R&D studies in pursuit of a Phase-2 end cap calorimeter upgrade.

Heavy Particles And Flavours - Proceedings Of Lishep 2018
Heavy Particles And Flavours - Proceedings Of Lishep 2018

Author: Alberto Santoro

Publisher: World Scientific

Published: 2019-07-30

Total Pages: 215

ISBN-13: 9811200394

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This book of proceedings is composed of articles based on the presentations at LISHEP 2018, centering on the main theme of the conference 'Heavy Particles and Flavours', with a focus on recent results and developments from the experiments at the Large Hadron Collider.

Multiple Parton Interactions At The Lhc
Multiple Parton Interactions At The Lhc

Author: Paolo Bartalini

Publisher: World Scientific Publishing

Published: 2018-11-02

Total Pages: 471

ISBN-13: 981322777X

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Many high-energy collider experiments (including the current Large Hadron Collider at CERN) involve the collision of hadrons. Hadrons are composite particles consisting of partons (quarks and gluons), and this means that in any hadron-hadron collision there will typically be multiple collisions of the constituents — i.e. multiple parton interactions (MPI). Understanding the nature of the MPI is important in terms of searching for new physics in the products of the scatters, and also in its own right to gain a greater understanding of hadron structure. This book aims at providing a pedagogical introduction and a comprehensive review of different research lines linked by an involvement of MPI phenomena. It is written by pioneers as well as young leading scientists, and reviews both experimental findings and theoretical developments, discussing also the remaining open issues.

Looking Inside Jets
Looking Inside Jets

Author: Simone Marzani

Publisher: Springer

Published: 2019-05-11

Total Pages: 210

ISBN-13: 3030157091

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This concise primer reviews the latest developments in the field of jets. Jets are collinear sprays of hadrons produced in very high-energy collisions, e.g. at the LHC or at a future hadron collider. They are essential to and ubiquitous in experimental analyses, making their study crucial. At present LHC energies and beyond, massive particles around the electroweak scale are frequently produced with transverse momenta that are much larger than their mass, i.e., boosted. The decay products of such boosted massive objects tend to occupy only a relatively small and confined area of the detector and are observed as a single jet. Jets hence arise from many different sources and it is important to be able to distinguish the rare events with boosted resonances from the large backgrounds originating from Quantum Chromodynamics (QCD). This requires familiarity with the internal properties of jets, such as their different radiation patterns, a field broadly known as jet substructure. This set of notes begins by providing a phenomenological motivation, explaining why the study of jets and their substructure is of particular importance for the current and future program of the LHC, followed by a brief but insightful introduction to QCD and to hadron-collider phenomenology. The next section introduces jets as complex objects constructed from a sequential recombination algorithm. In this context some experimental aspects are also reviewed. Since jet substructure calculations are multi-scale problems that call for all-order treatments (resummations), the bases of such calculations are discussed for simple jet quantities. With these QCD and jet physics ingredients in hand, readers can then dig into jet substructure itself. Accordingly, these notes first highlight the main concepts behind substructure techniques and introduce a list of the main jet substructure tools that have been used over the past decade. Analytic calculations are then provided for several families of tools, the goal being to identify their key characteristics. In closing, the book provides an overview of LHC searches and measurements where jet substructure techniques are used, reviews the main take-home messages, and outlines future perspectives.

From My Vast Repertoire...: Guido Altarelli's Legacy
From My Vast Repertoire...: Guido Altarelli's Legacy

Author: Stefano Forte

Publisher: World Scientific

Published: 2018-10-24

Total Pages: 465

ISBN-13: 9813238062

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'What makes this collection unusual and refreshing is that it is not the more common ‘Festschrift’ written by specialists for specialists, but a broad set of topical summaries and analyses addressed to a wide readership of particle physicists. Inevitably, some of the sections are more advanced in their treatment than others, but most of the material will be accessible and helpful to researchers at all levels, and in particular to those working on experiments at CERN, where Altarelli spent many years in the theory group. It is hard to do justice to the varied contents of this excellent collection … I can only recommend that anyone involved in particle research should turn to the web for a full description of the richness of material that is included here … There is something here for everyone, and much for most. I’m sure Altarelli would have been pleased with that! The Editors are to be complimented for their initiative in making this unique volume possible.'Contemporary PhysicsGuido Altarelli was a leading figure in 20th century particle physics. His scientific contributions and leadership played a key role in the development of the Standard Model of fundamental interactions, as well as the current search for new physics beyond it, both at and beyond CERN. This book is a collection of original contributions, at the cutting edge of scientific research, by some of the leading theoretical and experimental high-energy physicists currently in the field. These were inspired by Guido's ideas, whether directly or indirectly. This book is ideal for researchers looking to keep up with the latest developments in high-energy physics.

Foundations of Perturbative QCD
Foundations of Perturbative QCD

Author: John Collins

Publisher: Cambridge University Press

Published: 2011-04-28

Total Pages: 637

ISBN-13: 1139500627

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Giving an accurate account of the concepts, theorems and their justification, this book is a systematic treatment of perturbative QCD. It relates the concepts to experimental data, giving strong motivations for the methods. Ideal for graduate students starting their work in high-energy physics, it will also interest experienced researchers.