Search for Dark Matter with ATLAS
Search for Dark Matter with ATLAS

Author: Ruth Pöttgen

Publisher: Springer

Published: 2016-06-29

Total Pages: 325

ISBN-13: 3319410458

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This thesis describes in detail a search for weakly interacting massive particles as possible dark matter candidates, making use of so-called mono-jet events. It includes a detailed description of the run-1 system, important operational challenges, and the upgrade for run-2. The nature of dark matter, which accounts for roughly 25% of the energy-matter content of the universe, is one of the biggest open questions in fundamental science. The analysis is based on the full set of proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider at √s = 8 TeV. Special attention is given to the experimental challenges and analysis techniques, as well as the overall scientific context beyond particle physics. The results complement those of non-collider experiments and yield some of the strongest exclusion bounds on parameters of dark matter models by the end of the Large Hadron Collider run-1. Details of the upgrade of the ATLAS Central Trigger for run-2 are also included.

At the Edge of Time
At the Edge of Time

Author: Dan Hooper

Publisher: Princeton University Press

Published: 2019-11-05

Total Pages: 248

ISBN-13: 0691197008

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A new look at the first few seconds after the Big Bang—and how research into these moments continues to revolutionize our understanding of our universe Scientists in the past few decades have made crucial discoveries about how our cosmos evolved over the past 13.8 billion years. But there remains a critical gap in our knowledge: we still know very little about what happened in the first seconds after the Big Bang. At the Edge of Time focuses on what we have recently learned and are still striving to understand about this most essential and mysterious period of time at the beginning of cosmic history. Delving into the remarkable science of cosmology, Dan Hooper describes many of the extraordinary and perplexing questions that scientists are asking about the origin and nature of our world. Hooper examines how we are using the Large Hadron Collider and other experiments to re-create the conditions of the Big Bang and test promising theories for how and why our universe came to contain so much matter and so little antimatter. We may be poised to finally discover how dark matter was formed during our universe’s first moments, and, with new telescopes, we are also lifting the veil on the era of cosmic inflation, which led to the creation of our world as we know it. Wrestling with the mysteries surrounding the initial moments that followed the Big Bang, At the Edge of Time presents an accessible investigation of our universe and its origin.

An Introduction to Particle Dark Matter
An Introduction to Particle Dark Matter

Author: Stefano Profumo

Publisher: Wspc (Europe)

Published: 2017

Total Pages: 270

ISBN-13: 9781786340009

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Particle dark matter: the name of the game -- The thermal relic paradigm: zeroth-order lessons from cosmology -- The thermal relic paradigm: a closer look -- The art of WIMP direct detection -- Indirect dark matter searches -- Searching for dark matter with particle colliders -- Axions and axion-like particles as dark matter -- Sterile neutrinos as dark matter particles -- Bestiarium: a short, biased compendium of notable dark matter particle candidates and models

Search for Supersymmetry in pp Collisions at √s = 8 TeV with a Photon, Lepton, and Missing Transverse Energy
Search for Supersymmetry in pp Collisions at √s = 8 TeV with a Photon, Lepton, and Missing Transverse Energy

Author: Yutaro Iiyama

Publisher: Springer

Published: 2017-06-14

Total Pages: 182

ISBN-13: 3319586610

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This Ph.D. thesis is a search for physics beyond the standard model (SM) of particle physics, which successfully describes the interactions and properties of all known elementary particles. However, no particle exists in the SM that can account for the dark matter, which makes up about one quarter of the energy-mass content of the universe. Understanding the nature of dark matter is one goal of the CERN Large Hadron Collider (LHC). The extension of the SM with supersymmetry (SUSY) is considered a promising possibilities to explain dark matter. The nominated thesis describes a search for SUSY using data collected by the CMS experiment at the LHC. It utilizes a final state consisting of a photon, a lepton, and a large momentum imbalance probing a class of SUSY models that has not yet been studied extensively. The thesis stands out not only due to its content that is explained with clarity but also because the author performed more or less all aspects of the thesis analysis by himself, from data skimming to limit calculations, which is extremely rare, especially nowadays in the large LHC collaborations.

Dark Cosmos
Dark Cosmos

Author: Dan Hooper

Publisher: Harper Collins

Published: 2009-01-09

Total Pages: 258

ISBN-13: 0061976865

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The twentieth century was astonishing in all regards, shaking the foundations of practically every aspect of human life and thought, physics not least of all. Beginning with the publication of Albert Einstein's theory of relativity, through the wild revolution of quantum mechanics, and up until the physics of the modern day (including the astonishing revelation, in 1998, that the Universe is not only expanding, but doing so at an ever-quickening pace), much of what physicists have seen in our Universe suggests that much of our Universe is unseen—that we live in a dark cosmos. Everyone knows that there are things no one can see—the air you're breathing, for example, or, to be more exotic, a black hole. But what everyone does not know is that what we can see—a book, a cat, or our planet—makes up only 5 percent of the Universe. The rest—fully 95 percent—is totally invisible to us; its presence discernible only by the weak effects it has on visible matter around it. This invisible stuff comes in two varieties—dark matter and dark energy. One holds the Universe together, while the other tears it apart. What these forces really are has been a mystery for as long as anyone has suspected they were there, but the latest discoveries of experimental physics have brought us closer to that knowledge. Particle physicist Dan Hooper takes his readers, with wit, grace, and a keen knack for explaining the toughest ideas science has to offer, on a quest few would have ever expected: to discover what makes up our dark cosmos.

Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks at ATLAS
Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks at ATLAS

Author: Yangyang Cheng

Publisher: Springer

Published: 2016-09-29

Total Pages: 183

ISBN-13: 331944218X

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This thesis reports on the search for dark matter in data taken with the ATLAS detector at CERN’s Large Hadron Collider (LHC). The identification of dark matter and the determination of its properties are among the highest priorities in elementary particle physics and cosmology. The most likely candidate, a weakly interacting massive particle, could be produced in the high energy proton-proton collisions at the LHC. The analysis presented here is unique in looking for dark matter produced together with a Higgs boson that decays into its dominant decay mode, a pair of b quarks. If dark matter were seen in this mode, we would learn directly about the production mechanism because of the presence of the Higgs boson. This thesis develops the search technique and presents the most stringent production limit to date.

Search for Dark Matter with the ATLAS Detector
Search for Dark Matter with the ATLAS Detector

Author: Johanna Gramling

Publisher: Springer

Published: 2018-08-01

Total Pages: 290

ISBN-13: 3319950169

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This book discusses searches for Dark Matter at the CERN’s LHC, the world’s most powerful accelerator. It introduces the relevant theoretical framework and includes an in-depth discussion of the Effective Field Theory approach to Dark Matter production and its validity, as well as an overview of the formalism of Simplified Dark Matter models. Despite overwhelming astrophysical evidence for Dark Matter and numerous experimental efforts to detect it, the nature of Dark Matter still remains a mystery and has become one of the hottest research topics in fundamental physics. Two searches for Dark Matter are presented, performed on data collected with the ATLAS experiment. They analyze missing-energy final states with a jet or with top quarks. The analyses are explained in detail, and the outcomes and their interpretations are discussed, also in view of the precedent analysis of theoretical approaches. Given its depth of coverage, the book represents an excellent reference guide for all physicists interested in understanding the theoretical and experimental considerations relevant to Dark Matter searches at the LHC.

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

Published: 2016-09-21

Total Pages: 271

ISBN-13: 3319449567

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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.

The Physics of the Dark Photon
The Physics of the Dark Photon

Author: Marco Fabbrichesi

Publisher: Springer Nature

Published: 2020-11-23

Total Pages: 85

ISBN-13: 3030625192

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This book is about the dark photon which is a new gauge boson whose existence has been conjectured. Due to its interaction with the ordinary, visible photon, such a particle can be experimentally detected via specific signatures. In this book, the authors review the physics of the dark photon from the theoretical and experimental point of view. They discuss the difference between the massive and the massless case, highlighting how the two phenomena arise from the same vector portal between the dark and the visible sector. A review of the cosmological and astrophysical observations is provided, together with the connection to dark matter physics. Then, a perspective on current and future experimental limits on the parameters of the massless and massive dark photon is given, as well as the related bounds on milli-charged fermions. The book is intended for graduate students and young researchers who are embarking on dark photon research, and offers them a clear and up-to-date introduction to the subject.

Electroweak Gauginos with Highly Boosted Hadronically Decaying Bosons at the LHC
Electroweak Gauginos with Highly Boosted Hadronically Decaying Bosons at the LHC

Author: Yuta Okazaki

Publisher: Springer Nature

Published: 2023-01-01

Total Pages: 230

ISBN-13: 9811965935

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Supersymmetry (SUSY) introduces superpartners of the Standard Model (SM) particles. If their masses are typically O(100 GeV) ∼ O(TeV), a lightest neutralino can be a candidate for the dark matter, and the problem is solved by canceling the correction of the Higgs boson mass. Further, SUSY can explain the experimental result of the muon magnetic moment (g-2). This book presents a search for electroweakinos—the superpartners of the SM electroweak bosons—such as charginos and neutralinos using data at the LHC collected by the ATLAS detector. Pair-produced electroweakinos decay into the light ones and SM bosons (W/Z/h), and with the large mass difference between the heavy and light electroweakinos, the SM bosons have high momenta. In a fully hadronic final state, quarks decayed from the bosons are collimated, and can consequently be reconstructed as a single large-radius jet. This search has three advantages. The first is a statistical benefit by large branching ratios of the SM bosons. The second is to use characteristic signatures—the mass and substructure—of jets to identify as the SM bosons. The last is a small dependency on the signal model by targeting all the SM bosons. Thanks to them, the sensitivity is significantly improved compared to the previous analyses. Exclusion limits at the 95% confidence level on the heavy electroweakino mass parameter are set as a function of the light electroweakino mass parameter. They are set on wino or higgsino production models with various assumptions, such as the branching ratio of their decaying and the type of lightest SUSY particle. These limits are the most stringent limits. Besides, this book provides the most stringent constraints on SUSY scenarios motivated by the dark matter, the muon g-2 anomaly, and the naturalness.