Standard Model Measurements with the ATLAS Detector

Standard Model Measurements with the ATLAS Detector
Author: Jana Nováková
Publisher: Springer Science & Business Media
Total Pages: 100
Release: 2013-08-30
Genre: Science
ISBN: 3319008102

This thesis deals with two main procedures performed with the ATLAS detector at the Large Hadron Collider (LHC). The noise description in the hadronic calorimeter TileCal represents a very valuable technical job. The second part presents a fruitful physics analysis - the cross section measurement of the process p+p → Z0 → τ + τ. The Monte Carlo simulations of the TileCal are described in the first part of the thesis, including a detailed treatment of the electronic noise and multiple interactions (so-called pile-up). An accurate description of both is crucial for the reconstruction of e.g. jets or hadronic tau-jets. The second part reports a Standard Model measurement of the Z0 → τ + τ process with the emphasis on the final state with an electron and a hadronically decaying tau-lepton. The Z0 → τ + τ channel forms the dominant background in the search for Higgs bosons decaying into tau lepton pairs, and thus the good understanding achieved here can facilitate more sensitive Higgs detection.

Measurement of the Inclusive Jet Cross Section with the ATLAS Detector at the Large Hadron Collider

Measurement of the Inclusive Jet Cross Section with the ATLAS Detector at the Large Hadron Collider
Author: Caterina Doglioni
Publisher: Springer Science & Business Media
Total Pages: 167
Release: 2012-07-28
Genre: Science
ISBN: 3642305385

Tests of the current understanding of physics at the highest energies achievable in man-made experiments are performed at CERN’s Large Hadron Collider. In the theory of the strong force within the Standard Model of particle physics - Quantum ChromoDynamics or QCD - confined quarks and gluons from the proton-proton scattering manifest themselves as groups of collimated particles. These particles are clustered into physically measurable objects called hadronic jets. As jets are widely produced at hadron colliders, they are the key physics objects for an early "rediscovery of QCD". This thesis presents the first jet measurement from the ATLAS Collaboration at the LHC and confronts the experimental challenges of precision measurements. Inclusive jet cross section data are then used to improve the knowledge of the momentum distribution of quarks and gluons within the proton and of the magnitude of the strong force.

Particle Physics Reference Library

Particle Physics Reference Library
Author: Christian W. Fabjan
Publisher: Springer Nature
Total Pages: 1083
Release: 2020
Genre: Elementary particles (Physics).
ISBN: 3030353184

This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. 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

The Search and Discovery of the Higgs Boson

The Search and Discovery of the Higgs Boson
Author: Luis Roberto Flores Castillo
Publisher: Morgan & Claypool Publishers
Total Pages: 104
Release: 2016-01-01
Genre: Science
ISBN: 1681741423

This book provides a general description of the search for and discovery of the Higgs boson (particle) at CERN’s Large Hadron Collider. The goal is to provide a relatively brief overview of the issues, instruments and techniques relevant for this search; written by a physicist who was directly involved. The Higgs boson mat be the one particle that was studied the most before its discovery and the story from postulation in 1964 to detection in 2012 is a fascinating one. The story is told here while detailing the fundamentals of particle physics.

Discovery Of The Higgs Boson

Discovery Of The Higgs Boson
Author: Aleandro Nisati
Publisher: World Scientific
Total Pages: 470
Release: 2016-08-26
Genre: Science
ISBN: 981442546X

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.

New Physics At The Large Hadron Collider - Proceedings Of The Conference

New Physics At The Large Hadron Collider - Proceedings Of The Conference
Author: Harald Fritzsch
Publisher: World Scientific
Total Pages: 457
Release: 2016-10-27
Genre: Science
ISBN: 981314551X

The Standard Theory of Particle Physics describes successfully the observed strong and electroweak interactions, but it is not a final theory of physics, since many aspects are not understood: (1) How can gravity be introduced in the Standard Theory? (2) How can we understand the observed masses of the leptons and quarks as well as the flavor mixing angles? (3) Why are the masses of the neutrinos much smaller than the masses of the charged leptons? (4) Is the new boson, discovered at CERN, the Higgs boson of the Standard Theory or an excited weak boson? (5) Are there new symmetries at very high energy, e.g. a broken supersymmetry? (6) Are the leptons and quarks point-like or composite particles? (7) Are the leptons and quarks at very small distances one-dimensional objects, e.g. superstrings? This proceedings volume comprises papers written by the invited speakers discussing the many important issues of the new physics to be discovered at the Large Hadron Collider.

A Search for Displaced Leptons in the ATLAS Detector

A Search for Displaced Leptons in the ATLAS Detector
Author: Lesya Horyn
Publisher: Springer Nature
Total Pages: 146
Release: 2022-02-07
Genre: Science
ISBN: 3030916723

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).

Physics with Electrons in the ATLAS Detector

Physics with Electrons in the ATLAS Detector
Author: Kurt Brendlinger
Publisher: Springer
Total Pages: 261
Release: 2018-01-30
Genre: Science
ISBN: 3319739301

This thesis presents two production cross-section measurements of pairs of massive bosons using final states with leptons, made with the ATLAS detector at the Large Hadron Collider. The first measurement, performed using data collected in 2012 at center-of-mass energy √ s = 8 TeV, is the first fiducial and differential cross-section measurement of the production of the Higgs Boson when it decays to four charged leptons (electrons or muons). The second measurement is the first fiducial and inclusive production cross-section measurement of WZ pairs at center-of-mass energy √ s = 13 TeV using final states with three charged leptons. A significant portion of the thesis focuses on the methods used to identify electrons from massive boson decay—important for many flagship measurements—and on assessing the efficiency of these particle identification techniques. The chapter discussing the WZ pair cross-section measurement provides a detailed example of an estimate of lepton background in the context of an analysis with three leptons in the final state.

Higgs, Supersymmetry and Dark Matter After Run I of the LHC

Higgs, Supersymmetry and Dark Matter After Run I of the LHC
Author: Béranger Dumont
Publisher: Springer
Total Pages: 271
Release: 2016-09-21
Genre: Science
ISBN: 3319449567

This work was nominated as an outstanding PhD thesis by the LPSC, Université Grenoble Alpes, France. The LHC Run 1 was a milestone in particle physics, leading to the discovery of the Higgs boson, the last missing piece of the so-called "Standard Model" (SM), and to important constraints on new physics, which challenge popular theories like weak-scale supersymmetry. This thesis provides a detailed account of the legacy of the LHC Run 1 ≤¥regarding these aspects. First, the SM and the need for its extension are presented in a concise yet revealing way. Subsequently, the impact of the LHC Higgs results on scenarios of new physics is assessed in detail, including a careful discussion of the relevant uncertainties. Two approaches are considered: generic modifications of the Higgs couplings, possibly arising from extended Higgs sectors or higher-dimensional operators; and tests of specific new physics models. Lastly, the implications of the null results of the searches for new physics are discussed with a particular focus on supersymmetric dark matter candidates. Here as well, two approaches are presented: the "simplified models" approach, and recasting by event simulation. This thesis stands out for its educational approach, its clear language and the depth of the physics discussion. The methods and tools presented offer readers essential practical tools for future research.