Aspects of Bottom-up Hidden Sector Models

Aspects of Bottom-up Hidden Sector Models PDF Author: Philipp Klose
Publisher: Presses universitaires de Louvain
ISBN: 2390610021
Category : Science
Languages : en
Pages : 220

Get Book

Book Description
The standard model (SM) of particle physics is a hugely successful theory of nature, but it is incomplete. E.g., it cannot explain finite SM neutrino masses or the origin of the primordial baryon asymmetry (BAU). One way to address such problems is to postulate the existence of new but hidden particles. This thesis studies such "hidden sectors" in two ways: 1) An effective theory approach, where electroweak (EW) and GeV scale portal effective theories (PETs) are constructed that couple the SM to a generic light hidden mediator of spin 0, 1⁄2, or 1. The EW scale PETs include all portal operators of dimension d≤5. The GeV scale PETs additionally include all leading order (LO) flavour changing portal operators of dimension d≤6,7. They are used to derive a LO PET chiral perturbation theory Lagrangian that describes hidden sector induced light meson transitions in fixed target experiments like NA62 or SHiP. 2) An investigation of the type-I seesaw model, which couples the SM to n≥2 sterile neutrinos that can generate a BAU via “leptogenesis”. It is shown that thermal and spectator effects can result in a sign-flip and strong relative enhancement of the BAU in high-scale leptogenesis with two hierarchical sterile neutrinos of vanishing initial abundance. Much lighter sterile neutrinos may be detected via lepton number violating (LNV) decays at colliders, but LNV decays could be suppressed relative to lepton number conserving decays for 't Hooft natural parameter choices. It is shown that the corresponding parameter space consists of three regions: (a)with unsuppressed LNV decays, (b)with suppressed LNV decays, (c)with suppressed and unsuppressed LNV decays.

Aspects of Bottom-up Hidden Sector Models

Aspects of Bottom-up Hidden Sector Models PDF Author: Philipp Klose
Publisher: Presses universitaires de Louvain
ISBN: 2390610021
Category : Science
Languages : en
Pages : 220

Get Book

Book Description
The standard model (SM) of particle physics is a hugely successful theory of nature, but it is incomplete. E.g., it cannot explain finite SM neutrino masses or the origin of the primordial baryon asymmetry (BAU). One way to address such problems is to postulate the existence of new but hidden particles. This thesis studies such "hidden sectors" in two ways: 1) An effective theory approach, where electroweak (EW) and GeV scale portal effective theories (PETs) are constructed that couple the SM to a generic light hidden mediator of spin 0, 1⁄2, or 1. The EW scale PETs include all portal operators of dimension d≤5. The GeV scale PETs additionally include all leading order (LO) flavour changing portal operators of dimension d≤6,7. They are used to derive a LO PET chiral perturbation theory Lagrangian that describes hidden sector induced light meson transitions in fixed target experiments like NA62 or SHiP. 2) An investigation of the type-I seesaw model, which couples the SM to n≥2 sterile neutrinos that can generate a BAU via “leptogenesis”. It is shown that thermal and spectator effects can result in a sign-flip and strong relative enhancement of the BAU in high-scale leptogenesis with two hierarchical sterile neutrinos of vanishing initial abundance. Much lighter sterile neutrinos may be detected via lepton number violating (LNV) decays at colliders, but LNV decays could be suppressed relative to lepton number conserving decays for 't Hooft natural parameter choices. It is shown that the corresponding parameter space consists of three regions: (a)with unsuppressed LNV decays, (b)with suppressed LNV decays, (c)with suppressed and unsuppressed LNV decays.

A Search for Exotic Higgs Decays

A Search for Exotic Higgs Decays PDF Author: Jackson Burzynski
Publisher: Springer Nature
ISBN: 3031304667
Category : Science
Languages : en
Pages : 201

Get Book

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.

Relativity, Particle Physics And Cosmology - Proceedings Of The Richard Arnowitt Fest

Relativity, Particle Physics And Cosmology - Proceedings Of The Richard Arnowitt Fest PDF Author: Roland E Allen
Publisher: World Scientific
ISBN: 981454390X
Category :
Languages : en
Pages : 394

Get Book

Book Description
This volume outlines the status of fundamental physics at the threshold of the 21st century. Some of the world's leading theorists and experimentalists discuss ongoing research on the following topics: M Theory, Superstring Theory, Supersymmetry and Supergravity, Quantum Gravity, Dark Matter in the Universe, Gravitational Radiation, Proton Decay, Higgs Physics, Cosmology, Bose-Einstein Condensation.

Argument in the Greenhouse

Argument in the Greenhouse PDF Author: Sujata Gupta
Publisher: Routledge
ISBN: 113475065X
Category : Science
Languages : en
Pages : 464

Get Book

Book Description
How can greenhouse gases be controlled and reduced? Will it be in time? This book adds a significant new contribution to the crucial climate change/global warming debate. Incorporating the key political and legal considerations into `real world' applied economic analysis, the authors provide a unique focus on the wider political economy of the problem. All the key issues of controlling climate change (costs, timing and degree of stabilisation, ecological taxt reform, developing countries, and evolution of international agreements), are placed firmly within the current legal and political context, with state-of-the-art economic techniques introduced to analyse different policy proposals. Covering both the developing and developed world, this book identifies important new policies to foster effective agreements on eissions and prevent global warming - realistic policies, likely to receive support at both international and domestic levels. be in time? This book adds a significant new contribution to the crucial climate change/global warming debate. Incorporating the key political and legal considerations into 'real world' applied economic analysis, the book's authors provide a unique focus on the wider political economy of the problem. All the key issues of controlling climate change (costs, timing and degree of stabilisation, ecological tax reform, developing countries and evolution of international agreements), are placed firmly within the current legal and political economy context, with state-of-the-art economic techniques introduced to analyse different policy proposals. Covering both the developing and developed world, this book identifies important new policies to foster effective agreements on emmissions and prevent global warming - realistic policies which are likely to receive support at both international and domestic levels.

The Standard Model and Beyond

The Standard Model and Beyond PDF Author: Paul Langacker
Publisher: CRC Press
ISBN: 1498763243
Category : Science
Languages : en
Pages : 786

Get Book

Book Description
This new edition of The Standard Model and Beyond presents an advanced introduction to the physics and formalism of the standard model and other non-abelian gauge theories. It provides a solid background for understanding supersymmetry, string theory, extra dimensions, dynamical symmetry breaking, and cosmology. In addition to updating all of the experimental and phenomenological results from the first edition, it contains a new chapter on collider physics; expanded discussions of Higgs, neutrino, and dark matter physics; and many new problems. The book first reviews calculational techniques in field theory and the status of quantum electrodynamics. It then focuses on global and local symmetries and the construction of non-abelian gauge theories. The structure and tests of quantum chromodynamics, collider physics, the electroweak interactions and theory, and the physics of neutrino mass and mixing are thoroughly explored. The final chapter discusses the motivations for extending the standard model and examines supersymmetry, extended gauge groups, and grand unification. Thoroughly covering gauge field theories, symmetries, and topics beyond the standard model, this text equips readers with the tools to understand the structure and phenomenological consequences of the standard model, to construct extensions, and to perform calculations at tree level. It establishes the necessary background for readers to carry out more advanced research in particle physics. Supplementary materials are provided on the author’s website and a solutions manual is available for qualifying instructors.

Countdown to Kyoto, Parts I-III

Countdown to Kyoto, Parts I-III PDF Author: United States. Congress. House. Committee on Science. Subcommittee on Energy and Environment
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1252

Get Book

Book Description


Neutrino Mass, Dark Matter, Gravitational Waves, Monopole Condensation, and Light Cone Quantization

Neutrino Mass, Dark Matter, Gravitational Waves, Monopole Condensation, and Light Cone Quantization PDF Author: Behram N. Kursunogammalu
Publisher: Springer Science & Business Media
ISBN: 1489915648
Category : Science
Languages : en
Pages : 388

Get Book

Book Description
The International Conference, Orbis Scientiae 1996, focused on the topics: The Neutrino Mass, Light Cone Quantization, Monopole Condensation, Dark Matter, and Gravitational Waves which we have adopted as the title of these proceedings. Was there any exciting news at the conference? Maybe, it depends on who answers the question. There was an almost unanimous agreement on the overall success of the conference as was evidenced by the fact that in the after-dinner remarks by one of us (BNK) the suggestion of organizing the conference on a biannual basis was presented but not accepted: the participants wanted the continuation of the tradition to convene annually. We shall, of course, comply. The expected observation of gravitational waves will constitute the most exciting vindication of Einstein's general relativity. This subject is attracting the attention of the experimentalists and theorists alike. We hope that by the first decade of the third millennium or earlier, gravitational waves will be detected, opening the way for a search for gravitons somewhere in the universe, presumably through the observations in the CMBR. The theoretical basis of the graviton search will take us to quantum gravity and eventually to the modification of general relativity to include the Planck scale behavior of gravity -at energies 19 of the order of 10 Ge V.

String Theory and the Real World: From particle physics to astrophysics

String Theory and the Real World: From particle physics to astrophysics PDF Author:
Publisher: Elsevier
ISBN: 0080951511
Category : Science
Languages : en
Pages : 693

Get Book

Book Description
This book is a collection of lectures given in July 2007 at the Les Houches Summer School on "String Theory and the Real World: From particle physics to astrophysics." Provides a pedagogical introduction to topics in String Theory, and Cosmology Addresses each topic from the basis to the most recent developments Covers the lectures by internationally-renowned and leading experts

Predicted and Totally Unexpected in the Energy Frontier Opened by LHC

Predicted and Totally Unexpected in the Energy Frontier Opened by LHC PDF Author: Antonino Zichichi
Publisher: World Scientific
ISBN: 9814340219
Category : Science
Languages : en
Pages : 685

Get Book

Book Description
Antonino Zichichi has contributed to Predicted and Totally Unexpected in the Energy Frontier Opened by Lhc as an editor.Zichichi-Univ of Bologna, Italy, Natl Inst of Nuclear Physics, Italy

Perspectives On String Phenomenology

Perspectives On String Phenomenology PDF Author: Gordon Kane
Publisher: World Scientific
ISBN: 9814602698
Category : Science
Languages : en
Pages : 446

Get Book

Book Description
The remarkable recent discovery of the Higgs boson at the CERN Large Hadron Collider completed the Standard Model of particle physics and has paved the way for understanding the physics which may lie beyond it. String/M theory has emerged as a broad framework for describing a plethora of diverse physical systems, which includes condensed matter systems, gravitational systems as well as elementary particle physics interactions. If string/M theory is to be considered as a candidate theory of Nature, it must contain an effectively four-dimensional universe among its solutions that is indistinguishable from our own. In these solutions, the extra dimensions of string/M theory are “compactified” on tiny scales which are often comparable to the Planck length. String phenomenology is the branch of string/M theory that studies such solutions, relates their properties to data, and aims to answer many of the outstanding questions of particle physics beyond the Standard Model.This book contains perspectives on string phenomenology from some of the leading experts in the field. Contributions will range from pedagogical general overviews and perspectives to more technical reviews. We hope that the reader will get a sense of the significant progress that has been made in the field in recent years (e.g. in the topic of moduli stabilization) as well as the topics currently being researched, outstanding problems and some perspectives for the future.