Author: Jackson Burzynski Publisher: Springer Nature ISBN: 3031304667 Category : Science Languages : en Pages : 201
Book Description
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: Juha Äystö Publisher: Springer Science & Business Media ISBN: 3642555608 Category : Science Languages : en Pages : 507
Book Description
The ENAM2001 Conference was held on July 2-7, 2001 at the Rantasipi Aulanko Hotel in Hameenlinna in southern Finland. The conference was organized by the Department of Physics and the Accelerator Laboratory of the University of Jyvaskyla with support from the Physics Departments of the Universities of Helsinki and Turku. This conference, Exotic Nuclei and Atomic Masses has now gained the status of a major nuclear physics serial conference. The previous conference was held in Bellaire, Michigan, USA. The conference was first held in 1967 in Lysekil, Sweden, then entitled Conference on Nuclei Far from Stability. ENAM2001 welcomed 270 participants from 34 countries, including 17 accompanying per sons. The content of the program was selected based on the advice of the International Advisory Committee. The Committee members read and considered 253 submitted abstracts in selecting oral contributions. During the conference week 76 invited and oral talks were given. The rest of the contributions were presented in dedicated poster sessions. Many thanks go to the speakers of oral and poster presentations for their enthusiasm and for the high quality of their work which demonstrated the liveliness of the field. Participation in the lectures was high and contributions from the audience were important towards the success of this conference. The organizers would like to especially thank Cary Davids of Argonne National Laboratory for his comprehensive summary talk, which is also included in these Proceedings.
Author: Klaus Jungmann Publisher: Springer Science & Business Media ISBN: 3642779603 Category : Science Languages : en Pages : 313
Book Description
This volume comprises a collection of invited papers presented at the interna tional symposium "The Future of Muon Physics", May 7-9 1991, at the Ruprecht Karls-Universitat in Heidelberg. In the inspiring atmosphere of the Internationales Wissenschaftsforum researchers working worldwide at universities and at many inter national accelerator centers came together to review the present status of the field and to discuss the future directions in muon physics. The muon, charged lepton of the second generation, was first oberved some sixty years ago~ Despite many efforts since, the reason for its existence still remains a secret to the scientific community challenging both theorists and experimentalists. In modern physics the muon plays a key role in many topics of research. Atomic physics with negative muons provides excellent tests of the theory of quantum electrodynamics and of the electro-weak interaction and probes nuclear properties. The. purely leptonic hydrogen-like muonium atom allows tests of fun damental laws in physics and the determination of precise values for fundamental constants. New measurements of the anomalous magnetic moment of the muon will probe the renormalizability of the weak interaction and will be sensitive to physics beyond the standard model. The muon decay is the most carefully studied weak process. Searches for rare decay modes of muons and for the conversion of muonium to antimuonium examine the lepton number conservation laws and new speculative theories. Nuclear muon capture addresses fundamental questions like tests of the CPT theorem.
Author: Giorgio Benedek Publisher: Springer Science & Business Media ISBN: 3642763707 Category : Science Languages : en Pages : 299
Book Description
"Exotic Atoms in Condensed Matter" reviews the state of the art in this field, from meson factories to the basic interactions of muons in condensed matter. The application of muon- and pion-based analysis of solid state structural, magnetic and superconducting properties is discussed. The spectroscopic features of exotic atoms are reviewed together with their application to chemical analysis. Also, muon-catalyzed fusion is presented.
Author: K K Gan Publisher: World Scientific ISBN: 9814553433 Category : Languages : en Pages : 590
Book Description
The II International Workshop on Tau Lepton Physics was held in Ohio, USA in September 1992. Its purpose is to gather the experts on tau lepton physics to examine the current understanding of the tau lepton physics and to assess future prospects. A particular emphasis of the Workshop was a detailed examination of the '1-prong problem': the discrepancy between the inclusive measurement of one-charged-particle decay branching ratio and the sum of the exclusive decays. The Workshop also stimulated new ideas on tests of the Standard Model using the third generation lepton and assessed the future prospects of the lepton physics.
Author: Michael Andrews Publisher: Springer Nature ISBN: 3031250915 Category : Science Languages : en Pages : 193
Book Description
This book describes the first application at CMS of deep learning algorithms trained directly on low-level, “raw” detector data, or so-called end-to-end physics reconstruction. Growing interest in searches for exotic new physics in the CMS collaboration at the Large Hadron Collider at CERN has highlighted the need for a new generation of particle reconstruction algorithms. For many exotic physics searches, sensitivity is constrained not by the ability to extract information from particle-level data but by inefficiencies in the reconstruction of the particle-level quantities themselves. The technique achieves a breakthrough in the reconstruction of highly merged photon pairs that are completely unresolved in the CMS detector. This newfound ability is used to perform the first direct search for exotic Higgs boson decays to a pair of hypothetical light scalar particles H→aa, each subsequently decaying to a pair of highly merged photons a→yy, an analysis once thought impossible to perform. The book concludes with an outlook on potential new exotic searches made accessible by this new reconstruction paradigm.
Author: Hans V. Klapdor Publisher: Springer Science & Business Media ISBN: 3642736793 Category : Science Languages : en Pages : 339
Book Description
Neutrinos play an intriguing role in modern physics linking central questions of particle physics, cosmology and astrophysics. The contributions in this book reflect the present status of neutrino physics with emphasis on non-accelerator or beyond-accelerator experiments. Since a nonvanishing neutrino mass would yield an important boundary condition for GUT, SUSY or Superstring models and since neutrinos are the best candidates for dark matter in the universe, the many efforts to look for a neutrino mass, ranging from neutrino oscillation experiments using reactors, accelerators or the sun as neutrino sources, to tritium decay experiments and the search for neutrinoless double beta decay, are described in some detail. One of the sections is devoted to neutrinos from collapsing stars, including the supernova SN 1987 A. Possibilities for detecting cosmological neutrinos are discussed and an outlook to future experiments is given.
Author: Paul Bühler Publisher: Springer Science & Business Media ISBN: 9400748906 Category : Science Languages : en Pages : 330
Book Description
Proceedings of the International Conference on Exotic Atoms and Related Topics (EXA 2011) held in Vienna, Austria, September 5-9, 2011 E.Widmann and O. Hartmann (Eds) Now the research in exotic atoms has a remarkable history of more than 50 years. Enormous success in the understanding of fundamental interactions and symmetries resulted from the research on these tiny objects at the femtoscale. This volume contains research papers on recent achievements and future opportunities of this highly interdisciplinary field of atomic, nuclear, and particle physics. The Proceedings are structured according to the conference session topics: Kaon-Nucleus and Kaon-Nucleon Interactions, Antihydrogen and Fundamental Symmetries, Hadronphysics with Antiprotons, Future Facilities and Instrumentation, Low energy QCD. Reprint from Hyperfine Interactions vol. 209, 210 and 211.
Author: Jackson Burzynski
Author: Juha Äystö
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Author: Klaus Jungmann
Author: Giorgio Benedek
Author: K K Gan
Author: Michael Andrews
Author: Hans V. Klapdor
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Author: Paul Bühler