Search Results

Introduction

GÜNTHER DISSERTORI, IAN G. KNOWLES, and MICHAEL SCHMELLING

in Quantum Chromodynamics: High Energy Experiments and Theory

This introductory chapter sets the stage for particle physics. It discusses fundamental fields and interactions and puts these into perspective.

THE LINK TO THEORY

M. S. Sozzi

in Discrete Symmetries and CP Violation: From Experiment to Theory

This chapter provides a brief description of the way CP violation is accommodated in the Standard Model (SM) of particle physics. Some SM predictions for CP-violating observables are mentioned, and ... More

This chapter provides a brief description of the way CP violation is accommodated in the Standard Model (SM) of particle physics. Some SM predictions for CP-violating observables are mentioned, and conversely, the information in which measurements of CP violation can provide about its parameters is discussed. How CP violation could arise in different ways is described. Further reading topics and exercises are provided at the end of the chapter.Less

Models of Strongly Interacting Quantum Matter

Hans-Peter Eckle

in Models of Quantum Matter: A First Course on Integrability and the Bethe Ansatz

This chapter introduces a select number of models of strongly interacting quantum many-particle physics and examines their basic properties. These models represent Bosonic and Fermionic systems as ... More

This chapter introduces a select number of models of strongly interacting quantum many-particle physics and examines their basic properties. These models represent Bosonic and Fermionic systems as well as systems where magnetic moments, i.e. spins, interact. The main selection criterion has been the existence of a variant of the model that is quantum integrable using Bethe ansatz methods. After studying the Bose fluid, the Landau Fermi liquid, and the one-dimensional concept of the Luttinger liquid, it reviews some of the major models of condensed matter theory, including the Hubbard model describing itinerant magnetism, the Heisenberg model describing localized magnetism, and the Kondo model describing the interaction of a magnetic impurity and band electrons. It also presents the Rabi model and some of its descendants in order to describe the interaction of light and quantum matter in quantum optics.Less

Quantum Many-Particle Systems and Second Quantization

Hans-Peter Eckle

in Models of Quantum Matter: A First Course on Integrability and the Bethe Ansatz

Chapter 2 provides a review of pertinent aspects of the quantum mechanics of systems composed of many particles. It focuses on the foundations of quantum many-particle physics, the many-particle ... More

Chapter 2 provides a review of pertinent aspects of the quantum mechanics of systems composed of many particles. It focuses on the foundations of quantum many-particle physics, the many-particle Hilbert spaces to describe large assemblies of interacting systems composed of Bosons or Fermions, which lead to the versatile formalism of second quantization as a convenient and eminently practical language ubiquitous in the mathematical formulation of the theory of many-particle systems of quantum matter. The main objects in which the formalism of second quantization is expressed are the Bosonic or Fermionic creation and annihilation operators that become, in the position basis, the quantum field operators.Less

Introduction: Gut and Anti-Gut

VOLOVIK GRIGORY E.

in The Universe in a Helium Droplet

The book studies relations of condensed matter with particle physics and cosmology. The fundamental links between cosmology and particle physics have been well established and is widely exploited in ... More

The book studies relations of condensed matter with particle physics and cosmology. The fundamental links between cosmology and particle physics have been well established and is widely exploited in the description of the physics of the early universe (baryogenesis, cosmological nucleosynthesis, etc.). The connection of these two fields with the third ingredient of modern physics — condensed matter — allows us to simulate the least understood features of high-energy physics and cosmology: the properties of the quantum vacuum (also called aether, spacetime foam, quantum foam, Planck medium, etc.). The new concept inspired by condensed matter physics is opposite to the fundamental concept of broken symmetries used in Grand Unification Theory (GUT). In the anti-GUT scenario, gravity and the relativistic quantum field theory, such as the Standard Model of particle physics and GUT, are effective theories. They are emergent phenomena arising in the low-energy corner of the physical vacuum, where the system acquires physical laws and symmetries, which it did not have at higher energy.Less

Particle physics and cosmology

Pascal Pralavorio

in Post-Planck Cosmology: Lecture Notes of the Les Houches Summer School: Volume 100, July 2013

This chapter examines how it is possible to deduce consequences of particle physics for cosmology in light of the recent systematic exploration of the electroweak scale by experiments at the Large ... More

This chapter examines how it is possible to deduce consequences of particle physics for cosmology in light of the recent systematic exploration of the electroweak scale by experiments at the Large Hadron Collider (LHC). The two main results from the first phase of LHC, operation, namely, the discovery of a Higgs-like particle and the absence so far of new particles predicted by “natural” theories beyond the Standard Model (supersymmetry, extra dimensions and composite Higgs), are put in a historical context to highlight their importance, and are then presented in detail. For completeness, a short review of neutrino physics, which cannot be probed at the LHC, is also given. The ability of all these results to resolve the three fundamental questions of cosmology—the nature of dark energy and dark matter and the origin of matter–antimatter asymmetry—is discussed in each case.Less

INTRODUCTION TO SUPERSYMMETRY

John Terning

in Modern Supersymmetry: Dynamics and Duality

This chapter begins with a discussion of the standard model (SM) of particle physics. It then discusses SUSY algebra, SUSY representations, extended SUSY, and the further extension of extended SUSY ... More

This chapter begins with a discussion of the standard model (SM) of particle physics. It then discusses SUSY algebra, SUSY representations, extended SUSY, and the further extension of extended SUSY algebras with the addition of a ‘central charge”.Less

Relational Blockworld and Quantum Field Theory

Michael Silberstein, W.M. Stuckey, and Timothy McDevitt

in Beyond the Dynamical Universe: Unifying Block Universe Physics and Time as Experienced

A brief introduction to particle physics and quantum field theory (QFT) is presented in the main thread of chapter 5. The impasse of unification in particle physics is historically reviewed, showing ... More

A brief introduction to particle physics and quantum field theory (QFT) is presented in the main thread of chapter 5. The impasse of unification in particle physics is historically reviewed, showing that the dynamical paradigm pervades the development of particle physics and QFT. Thus, as with the conundrums of general relativity and quantum mechanics, dynamical explanation in the mechanical universe is responsible for the impasse regarding unification in particle physics as per QFT. It is shown that RBW’s adynamical approach provides an entirely new view of unification and particle physics. Philosophy of Physics for Chapter 5 uses RBW to resolve the interpretational issues of gauge invariance, gauge fixing, the Aharonov–Bohm effect, regularization, and renormalization, and largely discharges the problems of Poincaré invariance in a graphical approach, inequivalent representations, and Haag’s theorem. Foundational Physics for Chapter 5 shows how classical field theory is related to QFT and introduces gauge fields per QFT.Less

Doodling toward a New “Theory”

in Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics

In the spring of 1964, Jerry Finkelstein, a graduate student in Berkeley's physics department, summarized material culled from earlier course notes—courses that had covered several topics in ... More

In the spring of 1964, Jerry Finkelstein, a graduate student in Berkeley's physics department, summarized material culled from earlier course notes—courses that had covered several topics in theoretical particle physics, many of which his adviser, Geoffrey Chew, had first pioneered or championed only a few years earlier. Finkelstein's study notes comprised simple line drawings, though the diagrams looked to be Feynman diagrams to the casual observer. Finkelstein called the examples in his notes by different names such as Landau graphs, polology diagrams, and Cutkosky diagrams. This chapter discusses these examples in detail. Many particle theorists greeted the failure of perturbative techniques for the strong interactions by working with an alternative representation of particles' scatterings, in the form of dispersion relations. Theorists such as Murph Goldberger, Murray Gell-Mann, Francis Low, Geoffrey Chew, and Nambu Yoichiro launched the new phase of dispersion-relations work.Less

From Emergence to Complexity

Andrew Zangwill

in A Mind Over Matter: Philip Anderson and the Physics of the Very Many

Anderson was one of the first scientists to publicly challenge the claim by particle physicists that they deserved the lion’s share of federal funds for accelerators because their work was the most ... More

Anderson was one of the first scientists to publicly challenge the claim by particle physicists that they deserved the lion’s share of federal funds for accelerators because their work was the most ‘fundamental’. Anderson’s 1972 article “More is Different” challenged this idea and led to the idea of ‘emergence’ as a deep principle of Nature. He and Sam Edwards introduced a model for spin glass behavior and this activity dovetailed with his involvement in helping George Cowan, Murray Gell-Mann, Ken Arrow, and others create the Santa Fe Institute as a venue where complexity was celebrated as an organizing principle to solve difficult many-agent problems.Less

Quantum field theory: An effective theory

Jean Zinn-Justin

in From Random Walks to Random Matrices

Chapter 8 discusses effective field theory. This concept is inspired by the theory of critical phenomena in statistical physics and based on renormalization group ideas. The basic idea behind ... More

Chapter 8 discusses effective field theory. This concept is inspired by the theory of critical phenomena in statistical physics and based on renormalization group ideas. The basic idea behind effective field theory is that one starts from a microscopic model involving an infinite number of fluctuating degrees of freedom whose interactions are characterized by a microscopic scale and in which, as a result of interactions, a length that is much larger than the microscopic scale, or, equivalently, a mass much smaller than the characteristic mass scale of the initial model, is generated. The chapter illustrates this topic with examples. It also stresses that all quantum field theories as applied to particle physics or statistical physics are only effective (i.e. not fundamental) theories. Besides the problem of a phi4 type field theory with a large mass field, two more complicated examples are discussed: the Gross–Neveu and the non–linear sigma models.Less

Newtonianism, Reductionism and the Art of Congressional Testimony

Stephen Weinberg

in Emergence: Contemporary Readings in Philosophy and Science

This chapter discusses the philosophy of science as distinguished from a discussion about science itself. It attempts to show how the construction of a large new accelerator for elementary particle ... More

This chapter discusses the philosophy of science as distinguished from a discussion about science itself. It attempts to show how the construction of a large new accelerator for elementary particle physics, the Superconducting Supercollider, or SSC in the United States affects the direction of physics research as well as the philosophy of science in general. This accelerator opens up a new realm of high energy, the study of which is only made possible by the accelerator. A similar accelerator was built in Berkeley over 30 years ago, the Bevatron, which for the first time was capable of producing particles with masses of 1 GeV. The discovery of new physics is generally the main reason why these accelerators are built, but one can also point out specific discoveries that can be anticipated from a new accelerator as another reason.Less

The Structure of Science, Part 1

Andrew Steane

in Science and Humanity: A Humane Philosophy of Science and Religion

The first major theme of the book is introduced. This is that science does not present a ladder or tower of explanation, but a network of mutually interacting and informing ideas. The digital ... More

The first major theme of the book is introduced. This is that science does not present a ladder or tower of explanation, but a network of mutually interacting and informing ideas. The digital computer is invoked to introduce the concept of low-level and high-level language. The role of symmetry and symmetry principles in physics is discussed at length. It is argued, in agreement with Anderson, that symmetry is central to fundamental physics, but, more importantly, it is shown that what symmetry offers is a subtle constraining influence that is not the same as cause and effect, but is nevertheless central to the concept of explanation and understanding. It is argued that the laws of thermodynamics and the laws of particle physics are in a relationship of mutual consistency with neither able to render the other superfluous. Numerous examples are invoked.Less

Boisot and the God Particle

Marzio Nessi

in Knowledge, Organization, and Management: Building on the Work of Max Boisot

In a very personal reflective essay, Marzio Nessi, the technical coordinator of the ATLAS Collaboration at CERN, recounts Max Boisot’s work and interaction with the particle physics community at ... More

In a very personal reflective essay, Marzio Nessi, the technical coordinator of the ATLAS Collaboration at CERN, recounts Max Boisot’s work and interaction with the particle physics community at ATLAS and CERN, whose research on the Higgs particle, the famous “God particle”, has attracted a lot of media attention. Boisot was interested in the creation of knowledge at ATLAS and studied its unique organization, characterized by collaborative behavior, a bottom-up approach, and a consensus-driven management style, which has enabled this Big Science institution to create a new way of dealing with extreme complexity. Boisot was fascinated by how a scientific collaboration as large as ATLAS generates and sustains creative and constructive interactions among thousands of researchers from diverse cultures, traditions and habits. He believed that the self-organizational capability of the collaboration was the key to success. Boisot’s research also laid the ground for studying how scientific and technical progress is made and how the value of basic research can be captured for society.Less

What Is Matter Made Of?

Pauline Gagnon

in Who Cares about Particle Physics?: Making Sense of the Higgs Boson, the Large Hadron Collider and CERN

What are the smallest grains of matter and how do they interact to form the matter we observe around us? This chapter explains how matter is built from a handful of tiny “bricks” called fundamental ... More

What are the smallest grains of matter and how do they interact to form the matter we observe around us? This chapter explains how matter is built from a handful of tiny “bricks” called fundamental particles. Although twelve different bricks have been found, only three are needed to form all atoms found on Earth, in stars and in galaxies. The Standard Model is the current theoretical model that describes the fundamental particles and how they interact, giving us a clear representation of the material world. This model also predicts the behavior of these particles with a very high level of accuracy. Each particle comes with its own antiparticle. But why has nearly all the antimatter mysteriously disappeared from our Universe? Why are there useless bricks? These are some of the many puzzles described in this chapter that physicists are still trying to elucidate.Less