The highest-energy particle accelerator ever built, the Large Hadron Collider runs under the border between France and Switzerland. It leapt into action on September 10, 2008, amid unprecedented global press coverage and widespread fears that its energy would create tiny black holes that could destroy the earth. By smashing together particles smaller than atoms, the LHC recreates the conditions hypothesized to have existed just moments after the big bang. Physicists expect it to aid our understanding of how the universe came into being and to show us much about the standard model of particle physics—even possibly proving the existence of the mysterious Higgs boson. In exploring what the collider does and what it might find, Don Lincoln explains what the LHC is likely to teach us about particle physics, including uncovering the nature of dark matter, finding micro black holes and supersymmetric particles, identifying extra dimensions, and revealing the origin of mass in the universe. Thousands of physicists from around the globe will have access to the LHC, none of whom really knows what outcomes will be produced by the $7.7 billion project. Whatever it reveals, the results arising from the Large Hadron Collider will profoundly alter our understanding of the cosmos and the atom and stimulate amateur and professional scientists for years to come.

Describes the technology and engineering of the Large Hadron collider (LHC), one of the greatest scientific marvels of this young 21st century. This book traces the feat of its construction, written by the head scientists involved, placed into the context of the scientific goals and principles.

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.

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.

The Large Hadron Collider (LHC), located at CERN, Geneva, Switzerland, is the world's largest and highest energy and highest intensity particle accelerator. Here is a timely book with several perspectives on the hoped-for discoveries from the LHC.This book provides an overview on the techniques that will be crucial for finding new physics at the LHC, as well as perspectives on the importance and implications of the discoveries. Among the accomplished contributors to this book are leaders and visionaries in the field of particle physics beyond the Standard Model, including two Nobel Laureates (Steven Weinberg and Frank Wilczek), and presumably some future Nobel Laureates, plus top younger theorists and experimenters. With its blend of popular and technical contents, the book will have wide appeal, not only to physical scientists but also to those in related fields.

This book presents the first global interpretation of measurements of jet and top quark production at the Large Hadron Collider, including a simultaneous extraction of the standard model parameters together with constraints on new physics, unbiased from the assumptions on the standard model parameters. As a long-standing problem, any hadron collider search for new physics depends on parton distribution functions, which cannot be predicted but are extracted experimentally. However, performing the extraction in the same kinematic region where physics beyond the standard model is expected to manifest causes the risk of absorbing the new physics effects into the parton distributions. In this book, the issue is addressed by extending the standard model by effective contributions from quark contact interactions describing new physics and extracting the parton distributions and standard model parameters simultaneously with setting limits on the contact interactions. In the process, the most precise single measurement of the strong coupling constant at the LHC is performed, to date. Furthermore, the book details the first investigation of the mass renormalization scale dependence of the top quark mass, highlighting the importance of a proper scale choice for obtaining robust predictions and improving the precision of experimental analyses. The initial chapters provide the reader with a succinct yet accessible introduction to the relevant theoretical and experimental topics. The presented investigations are at the edge of precision in the phenomenology of high-energy physics and serve to pave the road toward a global interpretation of LHC data.

NAMED A BEST SCIENCE BOOK OF 2021 BY KIRKUS * An acclaimed experimental physicist at CERN takes you on an exhilarating search for the most basic building blocks of our universe, and the dramatic quest to unlock their cosmic origins. "A fascinating exploration of how we learned what matter really is, and the journey matter takes from the Big Bang, through exploding stars, ultimately to you and me." (Sean Carroll) Carl Sagan once quipped, “If you wish to make an apple pie from scratch, you must first invent the universe.” But finding the ultimate recipe for apple pie means answering some big questions: What is matter really made of? How did it escape annihilation in the fearsome heat of the Big Bang? And will we ever be able to understand the very first moments of our universe? In How to Make an Apple Pie from Scratch, Harry Cliff—a University of Cambridge particle physicist and researcher on the Large Hadron Collider—sets out in pursuit of answers. He ventures to the largest underground research facility in the world, deep beneath Italy's Gran Sasso mountains, where scientists gaze into the heart of the Sun using the most elusive of particles, the ghostly neutrino. He visits CERN in Switzerland to explore the "Antimatter Factory," where the stuff of science fiction is manufactured daily (and we're close to knowing whether it falls up). And he reveals what the latest data from the Large Hadron Collider may be telling us about the fundamental nature of matter. Along the way, Cliff illuminates the history of physics, chemistry, and astronomy that brought us to our present understanding—and misunderstandings—of the world, while offering readers a front-row seat to one of the most dramatic intellectual journeys human beings have ever embarked on. A transfixing deep dive into the origins of our world, How to Make an Apple Pie from Scratch examines not just the makeup of our universe, but the awe-inspiring, improbable fact that it exists at all.

Lincoln, a senior scientist at Fermi National Accelerator Laboratory and adjunct professor of physics at Notre Dame, gives readers an insider's view of the Hadron Collider from its conception, through its early discoveries and difficulties, to its greatest triumph, the discovery of the Higgs boson.

This book is written by the ATLAS Collaboration at CERN's Large Hadron Collider (LHC), to document and reflect on its more than 25 years of history. It covers all aspects of this global science project at the forefront of particle physics. The historical part recalls first the early stages of discussions in the community leading to the formation of the collaboration in 1992. In a unique approach, the second part documents the evolution from early detector concepts to the final instrument, covering the technical, financial and human aspects. This includes the phases of construction of detector components in the various institutes around the world as well as their installation and commissioning in the underground cavern at CERN.An important part is devoted to the operation of the whole experiment. The book highlights the capabilities and physics accomplishments so far, including the Higgs boson discovery (jointly announced with CMS). It features the various aspects of a broad spectrum of activities needed to arrive at the physics results. The book includes also an outlook to the detector upgrade activities preparing the experiment for the high-luminosity LHC phase of the next decades. Last but not least, it reveals the human aspects of the large ATLAS community working together pursuing common physics goals.The book is aimed at a broad readership with interest in large science projects and their history, as well as in the human endeavour of a worldwide collaboration.