A Search For Displaced Leptons In The Atlas Detector

Author : Lesya Horyn
Publisher : Springer Nature
Page : 146 pages
File Size : 47,8 Mb
Release : 2022-02-07
Category : Science
ISBN : 9783030916725

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A Search for Displaced Leptons in the ATLAS Detector by Lesya Horyn Pdf

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).

Author : Takuya Nobe
Publisher : Springer
Page : 224 pages
File Size : 50,5 Mb
Release : 2015-11-30
Category : Science
ISBN : 9789811000034

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Search for Scalar Top Quarks and Higgsino-Like Neutralinos by Takuya Nobe Pdf

This book reports a search for theoretically natural supersymmetry (SUSY) at the Large Hadron Collider (LHC). The data collected with the ATLAS detector in 2012 corresponding to 20 /fb of an integrated luminosity have been analyzed for stop pair production in proton–proton collisions at a center-of-mass energy of 8 TeV at the Large Hadron Collider (LHC) in the scenario of the higgsino-like neutralino. The author focuses on stop decaying into a bottom quark and chargino. In the scenario of the higgsino-like neutralino, the mass difference between charginos and neutralinos (Δm) is expected to be small, and observable final-state particles are likely to have low-momentum (soft). The author develops a dedicated analysis with a soft lepton as a probe of particles from chargino decay, which suppresses the large amount of backgrounds. As a result of the analysis, no significant SUSY signal is observed. The 95% confidence-level exclusion limits are set to masses of stop and neutralino assuming Δm = 20 GeV. The region with ΔM (the mass difference between stop and neutralino) 70 GeV is excluded for the first time at stop mass of less than 210 GeV. The author also excludes the signals with ΔM 120 GeV up to 600 GeV of stop mass with neutralino mass of less than 280 GeV. The author clearly shows very few remaining parameter spaces for light stop (e.g., topology of stop decay is extremely similar to the SM top quark) by combining his results and previous ATLAS analyses. His results provide a strong constraint to searches for new physics in the future.

Author : Elodie Resseguie
Publisher : Springer
Page : 322 pages
File Size : 51,8 Mb
Release : 2021-11-05
Category : Science
ISBN : 3030570185

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Electroweak Physics at the Large Hadron Collider with the ATLAS Detector by Elodie Resseguie Pdf

This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.

Author : Milena Ivanova,Alice Murphy
Publisher : Taylor & Francis
Page : 255 pages
File Size : 54,5 Mb
Release : 2023-06-16
Category : Philosophy
ISBN : 9781000900804

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The Aesthetics of Scientific Experiments by Milena Ivanova,Alice Murphy Pdf

The relationship between aesthetics and science has begun to generate substantial interest. However, for the most part, the focus has been on the beauty of theories, and other aspects of scientific practice have been neglected. This book offers a novel perspective on aesthetics in experimentation via ten original essays from an interdisciplinary group comprised of philosophers, historians of science and art, and artists. The collection provides an analysis of the concept of beauty in the evaluation of experiments. What properties do practising experimenters value? How have the aesthetic properties of scientific experiments changed over the years? Secondly, the volume looks at the role that aesthetic factors, including negative values such as ugliness, as well as experiences of the sublime and the profound, play in the construction of an experiment and its reception. Thirdly, the chapters provide in-depth historical case studies from the Royal Society, which also allows for a study of the depiction of scientific experiment in artworks, as well as contemporary examples from the Large Hadron Collider and cases of experiments designed by artificial intelligence. Finally, it offers an exploration of the commonalities between how we learn from experiments on the one hand and the cognitive value of artworks on the other. The Aesthetics of Scientific Experiments will be of interest to researchers and advanced students working in philosophy and history of science, philosophy and history of art, as well as practising scientists and science communicators.

Author : Alessandro Tricoli,Patrizia Azzi,Petra Merkel,Vladimir Shiltsev
Publisher : Frontiers Media SA
Page : 237 pages
File Size : 46,7 Mb
Release : 2023-07-21
Category : Science
ISBN : 9782832522028

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Novel ideas for accelerators, particle detection and data challenges at future colliders by Alessandro Tricoli,Patrizia Azzi,Petra Merkel,Vladimir Shiltsev Pdf

Author : Jackson Burzynski
Publisher : Springer Nature
Page : 201 pages
File Size : 48,8 Mb
Release : 2023-05-23
Category : Science
ISBN : 9783031304668

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A Search for Exotic Higgs Decays by Jackson Burzynski Pdf

The absence of new physics at the TeV scale observed thus far at the Large Hadron Collider (LHC) motivates an increasing focus on searches for weakly-coupled new particles and exotic signatures. In particular, particles with macroscopic mean proper lifetimes, known as long-lived particles (LLPs), are of significant interest due to their ability to elude the majority of searches which rely on the assumption that Beyond Standard Model particles decay close to the primary interaction point. Many models which aim to solve various issues with the Standard Model (SM) introduce new particles with lifetimes that are either unconstrained, or even shown to prefer the macroscopic regime. These theories often point to the Higgs boson as a possible portal to new physics, with exotic Higgs decays being the primary phenomenological consequence and means of discovery. It is well motivated both from theory and experimental constraints to consider the scenario in which the particles produced in these exotic decays have macroscopic proper lifetimes and give rise to unique detector signatures. This work describes a search for exotic decays of the Higgs boson to two long-lived, neutral, spin-0 particles which subsequently decay to pairs of b quarks, giving the striking signature of displaced hadronic jets in the ATLAS inner detector. Several other ATLAS searches have probed this decay topology previously, excluding branching ratios of the Higgs boson to LLPs of more than 10% for proper lifetimes greater than 100mm. These searches relied on dedicated triggers designed to select events with LLPs decaying in the ATLAS calorimeter or muon spectrometer. The lack of an equivalent trigger for LLP decays in the ATLAS inner detector has been a limiting factor in probing LLP lifetimes less than 100mm. To circumvent the difficulty of triggering on LLP decays, the search presented in this thesis exploits the ZH associated production mode, relying on leptonic trigger signatures to select interesting events. This is the first search for Higgs boson decays into LLPs to exploit this analysis methodology and additionally makes use of several novel methods for both background rejection and background estimation. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs . Depending on the mass of the LLP, branching ratios greater than 10% are excluded for lifetimes as small as 4mm and as large as 100mm, probing an important gap in the ATLAS exotic Higgs decay programme. In comparison to the previous searches for Higgs decays to LLPs, these are among the most stringent limits placed on this scenario, and for LLPs with masses below 40 GeV these results represent the strongest existing constraints on the branching ratio of the Higgs boson to LLPs in this lifetime regime.

Author : Wang Wei,Xing Zhi-zhong
Publisher : World Scientific
Page : 576 pages
File Size : 48,6 Mb
Release : 2020-02-27
Category : Science
ISBN : 9789811207419

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Lepton Photon Interactions At High Energies (Lepton Photon 2017) - Proceedings Of The 28th International Symposium by Wang Wei,Xing Zhi-zhong Pdf

The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.

Author : Lydia Audrey Beresford
Publisher : Springer
Page : 169 pages
File Size : 42,6 Mb
Release : 2018-09-04
Category : Science
ISBN : 9783319975207

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Searches for Dijet Resonances by Lydia Audrey Beresford Pdf

This book addresses one of the most intriguing mysteries of our universe: the nature of dark matter. The results presented here mark a significant and substantial contribution to the search for new physics, in particular for new particles that couple to dark matter. The first analysis presented is a search for heavy new particles that decay into pairs of hadronic jets (dijets). This pioneering analysis explores unprecedented dijet invariant masses, reaching nearly 7 TeV, and sets constraints on several important new physics models. The two subsequent analyses focus on the difficult low dijet mass region, down to 200 GeV, and employ a novel technique to efficiently gather low-mass dijet events. The results of these analyses transcend the long-standing constraints on dark matter mediator particles set by several existing experiments.

Author : Kurt Brendlinger
Publisher : Unknown
Page : 602 pages
File Size : 55,8 Mb
Release : 2016
Category : Electronic
ISBN : OCLC:982403190

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Physics with Electrons in the ATLAS Detector by Kurt Brendlinger Pdf

This thesis presents two diboson measurements with the ATLAS experiment. The first is a differential measurement of Higgs boson observables in the four-lepton decay channel at [square root]s=8 TeV. The second presents a first measurement of the WZ diboson production cross section in the three-lepton decay channel at [square root] s=13 TeV. Special emphasis is given to the identification techniques of prompt electrons, particularly the likelihood identification first introduced in 2012 data taking, and electron efficiency measurements in the ATLAS detector.

Author : Marilena Streit-Bianchi,Paola Catapano,Cristiano Galbiati,Enrico Magnani
Publisher : Springer Nature
Page : 382 pages
File Size : 54,6 Mb
Release : 2022-12-04
Category : Science
ISBN : 9783031056253

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Advances in Cosmology by Marilena Streit-Bianchi,Paola Catapano,Cristiano Galbiati,Enrico Magnani Pdf

Cosmology’s journey to the present day has been a long one. This book outlines the latest research on modern cosmology and related topics from world-class experts. Through it, readers will learn how multi-disciplinary approaches and technologies are used to search the unknown and how we arrived at the knowledge used and assumptions made by cosmologists today. The book is organized into four parts, each exploring a theme that has troubled humankind for centuries. Since the dawn of time, looking at the sky, humans have tried to understand their origin, the laws governing it, and what influence it all has on human life. In most ancient civilizations, astronomers embodied the power of knowledge. This knowledge was not compartmentalized, and scientists often found philosophical implications within their quests, many of which destroyed the borders between the natural sciences. Even now, as observers and scientists continue to use conjecture to generate theoretical assumptions and laws that then have to be confirmed experimentally, said theoretical and experimental searches are being linked to philosophical thinking and artistic representation, as they were up until the 18th century. This multi-disciplinary book will appeal to anyone with an interest in the fields of Astronomy, Cosmology or Physics.

Author : Oliver Bruning,Max Klein,Lucio Rossi,Paolo Spagnolo
Publisher : World Scientific
Page : 455 pages
File Size : 47,8 Mb
Release : 2023-08-08
Category : Science
ISBN : 9789811280191

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Future Of The Large Hadron Collider, The: A Super-accelerator With Multiple Possible Lives by Oliver Bruning,Max Klein,Lucio Rossi,Paolo Spagnolo Pdf

The Large Hadron Collider (LHC) is the highest energy collider ever built. It resides near Geneva in a tunnel 3.8m wide, with a circumference of 26.7km, which was excavated in 1983-1988 to initially house the electron-positron collider LEP. The LHC was approved in 1995, and it took until 2010 for reliable operation. By now, a larger set of larger integrated luminosities have been accumulated for physics analyses in the four collider experiments: ATLAS, CMS, LHCb and ALICE.The LHC operates with an extended cryogenic plant, using a multi-stage injection system comprising the PS and SPS accelerators (still in use for particle physics experiments at lower energies). The beams are guided by 1232 superconducting high field dipole magnets.Intense works are underway in preparation of the High Luminosity LHC, aimed at upgrading the LHC and detectors for collecting ten times more luminosity, and extending the collider life to the early 2040's. So far, the (HL-)LHC project represents a cumulation of around one hundred thousand person-years of innovative work by technicians, engineers, and physicists from all over the world; probably the largest scientific effort ever in the history of humanity. The book is driven by the realisation of the unique value of this accelerator complex and by the recognition of the status of high energy physics, described by a Standard Model — which still leaves too many questions unanswered to be the appropriate theory of elementary particles and their interactions.Following the Introduction are: three chapters which focus on the initial decade of operation, leading to the celebrated discovery of the Higgs Boson, on the techniques and physics of the luminosity upgrade, and finally on major options - of using the LHC in a concurrent, power economic, electron-hadron scattering mode, when upgraded to higher energies or eventually as an injector for the next big machine. The various technical and physics chapters, provided by 61 authors, characterise the fascinating opportunities the LHC offers for the next two decades ahead (possibly longer), with the goal to substantially advance our understanding of nature.

Author : Anjan Giri,Rukmani Mohanta
Publisher : Springer Nature
Page : 457 pages
File Size : 41,6 Mb
Release : 2020-09-01
Category : Science
ISBN : 9789811562921

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Workshop on Frontiers in High Energy Physics 2019 by Anjan Giri,Rukmani Mohanta Pdf

This book presents the proceedings of The International Workshop on Frontiers in High Energy Physics (FHEP 2019), held in Hyderabad, India. It highlights recent, exciting experimental findings from LHC, KEK, LIGO and several other facilities, and discusses new ideas for the unified treatment of cosmology and particle physics and in the light of new observations, which could pave the way for a better understanding of the universe we live in. As such, the book provides a platform to foster collaboration in order to provide insights into this important field of physics.

Author : Johanna Gramling
Publisher : Springer
Page : 282 pages
File Size : 45,9 Mb
Release : 2018-08-01
Category : Science
ISBN : 9783319950167

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Search for Dark Matter with the ATLAS Detector by Johanna Gramling Pdf

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.

Author : Roman Pasechnik,António Pestana Morais,Stefano Moretti
Publisher : Frontiers Media SA
Page : 180 pages
File Size : 43,7 Mb
Release : 2020-09-03
Category : Science
ISBN : 9782889639908

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Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like? by Roman Pasechnik,António Pestana Morais,Stefano Moretti Pdf

This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Author : Enrico Morgante
Publisher : Springer
Page : 212 pages
File Size : 49,8 Mb
Release : 2017-10-05
Category : Science
ISBN : 9783319676067

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Aspects of WIMP Dark Matter Searches at Colliders and Other Probes by Enrico Morgante Pdf

This thesis covers several theoretical aspects of WIMP (weakly interacting massive particles) dark matter searches, with a particular emphasis on colliders. It mainly focuses on the use of effective field theories as a tool for Large Hadron Collider (LHC) searches, discussing in detail the issue of their validity, and on simplified dark matter models, which are receiving a growing attention from the physics community. It highlights the theoretical consistency of simplified models, which is essential in order to correctly exploit their potential and for them to be a common reference when comparing results from different experiments. This thesis is of interest to researchers (both theorists and experimentalists) in the field of dark matter searches, and offers a comprehensive introduction to dark matter and to WIMP searches for students and non-experts.