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CERN Celebrates Discoveries
INTERNATIONAL JOURNAL OF HIGH-ENERGY PHYSICS CERN COURIER VOLUME 43 NUMBER 10 DECEMBER 2003 CERN celebrates discoveries NEW PARTICLES NETWORKS SPAIN Protons make pentaquarks p5 Measuring the digital divide pl7 Particle physics thrives p30 16 KPH impact 113 KPH impact series VISyN High Voltage Power Supplies When the objective is to measure the almost immeasurable, the VISyN-Series is the detector power supply of choice. These multi-output, card based high voltage power supplies are stable, predictable, and versatile. VISyN is now manufactured by Universal High Voltage, a world leader in high voltage power supplies, whose products are in use in every national laboratory. For worldwide sales and service, contact the VISyN product group at Universal High Voltage. Universal High Voltage Your High Voltage Power Partner 57 Commerce Drive, Brookfield CT 06804 USA « (203) 740-8555 • Fax (203) 740-9555 www.universalhv.com Covering current developments in high- energy physics and related fields worldwide CERN Courier (ISSN 0304-288X) is distributed to member state governments, institutes and laboratories affiliated with CERN, and to their personnel. It is published monthly, except for January and August, in English and French editions. The views expressed are CERN not necessarily those of the CERN management. Editor Christine Sutton CERN, 1211 Geneva 23, Switzerland E-mail: [email protected] Fax:+41 (22) 782 1906 Web: cerncourier.com COURIER Advisory Board R Landua (Chairman), P Sphicas, K Potter, E Lillest0l, C Detraz, H Hoffmann, R Bailey -
Arxiv:1809.08749V3 [Quant-Ph] 5 Dec 2018 a General Guiding Principle in Building the Theory of Fun- Damental Interactions (See, E.G., [1,3])
Resolution of Gauge Ambiguities in Ultrastrong-Coupling Cavity QED Omar Di Stefano,1 Alessio Settineri,2 Vincenzo Macr`ı,1 Luigi Garziano,1 Roberto Stassi,1 Salvatore Savasta,1, 2, ∗ and Franco Nori1, 3 1Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan 2Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Universit`adi Messina, I-98166 Messina, Italy 3Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA Gauge invariance is the cornerstone of modern quantum field theory [1{4]. Recently, it has been shown that the quantum Rabi model, describing the dipolar coupling between a two-level atom and a quantized electromagnetic field, violates this principle [5{7]. This widely used model describes a plethora of quantum systems and physical processes under different interaction regimes [8,9]. In the ultrastrong coupling regime, it provides predictions which drastically depend on the chosen gauge. This failure is attributed to the finite-level truncation of the matter system. We show that a careful application of the gauge principle is able to restore gauge invariance even for extreme light- matter interaction regimes. The resulting quantum Rabi Hamiltonian in the Coulomb gauge differs significantly from the standard model and provides the same physical results obtained by using the dipole gauge. It contains field operators to all orders that cannot be neglected when the coupling strength is high. These results shed light on subtleties of gauge invariance in the nonperturbative and extreme interaction regimes, which are now experimentally accessible, and solve all the long-lasting controversies arising from gauge ambiguities in the quantum Rabi and Dicke models [5, 10{18]. -
Background Information on the 1999 Nobel Prize in Physics Particle
Background information on the 1999 Nobel Prize in Physics Particle physics deals with the properties of the basic constituents of matter and the interactions between them. Up to now, the most successful “language” in this branch of physics has been that of relativistic quantum field theory. In this framework elementary particles are represented by (second quantized) fields, these being functions of space and time that include creation and annihilation operators for particles. For example light, the photon, is represented by such a field. These fields are thus the building blocks of theories that attempt to describe elementary particles and their interactions. A highly successful theory of this kind is Quantum Electrodynamics, commonly known as QED. QED describes, to a very high degree of accuracy, the interactions of electrons, positrons and light at low energies. It also enjoys a great deal of success in many other applications, for example when it is used to describe the interaction of light with atoms. However, the development of QED and understanding its quantum structure did not come easily but took several decades. The theory was to be used perturbatively. In other words, taking into account higher order corrections was expected to improve the accuracy of its predictions. But instead some of these corrections were found to be infinitely large. Many scientists contributed to elucidating and solving the problems of QED, among them R. P. Feynman, J. Schwinger and S.-I. Tomonaga who shared the 1965 Nobel Prize in Physics for “their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles”. -
Meetings Klaus Schultze
People Meetings • The Sixth International Wigner Symposium (WigSym6) will be held in Istanbul,Turkey, on 16-22 August as part of the ongoing biennial series of International Wigner symposia. Concentrating on quantum and conformal field theory, strings and quantum groups, the even will be held at Bogazici University on one of the hills of Bosphorus. Internet "http:// www.wigsym6.boun.edu.tr". E-mail "wigsym6 @boun.edu.tr". For an automated answering service, e-mail "<[email protected]>" with WIGSYM.99 on the subject line. The American Physical Society (APS) Centennial meeting in Atlanta on 20-26 March, • The Ninth Lomonosov Conference on attended by some 11400, physicists was the largest physics meeting in history. At the Elementary Particle Physics, organized by the event, Cecilia Jarlskog of CERN (with microphone), who chairs the Nobel Committee for Interregional Centre for Advanced Studies, Physics and Chemistry, opened a photographic gallery of physics laureates. On the right is Moscow; the Faculty of Physics, the Institute APS President and 1990 Nobel Prize for Physics winner Jerome Friedman. of Theoretical Microphysics of the Moscow State University; the Joint Institute for Nuclear Research, Dubna; the Instituto Superior Tecnico - CENTRA, Lisbon; the Institute of Theoretical and Experimental Physics, Moscow; Klaus Schultze the Institute for High Energy Physics, Protvino; and the Institute for Nuclear Research, Enthusiastic and committed physicist Klaus Moscow) will be held at Moscow State Schultze died on 8 April aged 67. University, Moscow, from 20-26 September. After receiving his doctorate at Wurzburg Topics will include electroweak theory, tests of with a thesis on the range of electrons in a the standard model and beyond, heavy quark heavy liquid bubble chamber, Schultze physics, non-perturbative QCD, neutrino became a CERN fellow in 1962, joining the physics, astroparticle physics and quantum NPA heavy liquid bubble chamber group. -
Gauge Principle and QED∗
Gauge Principle and QED¤ Norbert Straumann Institute for Theoretical Physics University of Zurich,¨ Switzerland August, 2005 Abstract One of the major developments of twentieth century physics has been the gradual recognition that a common feature of the known fundamental inter- actions is their gauge structure. In this talk the early history of gauge theory is reviewed, emphasizing especially Weyl’s seminal contributions of 1918 and 1929. 1 Introduction The organizers of this conference asked me to review the early history of gauge theories. Because of space and time limitations I shall concentrate on Weyl’s seminal papers of 1918 and 1929. Important contributions by Fock, Klein and others, based on Kaluza’s five-dimensional unification attempt, will not be dis- cussed. (For this I refer to [30] and [31].) The history of gauge theories begins with GR, which can be regarded as a non- Abelian gauge theory of a special type. To a large extent the other gauge theories emerged in a slow and complicated process gradually from GR. Their common geometrical structure – best expressed in terms of connections of fiber bundles – is now widely recognized. It all began with H. Weyl [2] who made in 1918 the first attempt to extend GR in order to describe gravitation and electromagnetism within a unifying geomet- rical framework. This brilliant proposal contains the germs of all mathematical ¤Invited talk at PHOTON2005, The Photon: Its First Hundred Years and the Future, 31.8- 04.09, 2005, Warsaw. 1 aspects of non-Abelian gauge theory. The word ‘gauge’ (german: ‘Eich-’) trans- formation appeared for the first time in this paper, but in the everyday meaning of change of length or change of calibration. -
VI BRAZILIAN SYMPOSIUM on THEORETICAL PHYSICS Erasmo Ferreira, Belita Koiller, Editors
VI BRAZILIAN SYMPOSIUM ON THEORETICAL PHYSICS Erasmo Ferreira, Belita Koiller, Editors Elementary Particle Physics and Relativity CG. Bollini, J.J Giambiagi, A.A. Salam, S.W. Mac Dowell, CO. Escobar, R. Chanda, B. Schroer, Contributors VOLUME III CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO u &, J" li ¥?. I 0 Ki ^.. Li Erasmo Ferreira, Belita Koiller, Editors Elementary Particle Physics and Relativity CG. Bollini, J.J. Giambiagi, A.A. Saiam, S.W. Mac DoweSI. CO. Escobar, R. Chanda, B. Schroer, Contributors VOLUME III CONSELHO NACIONAL DE DESENVOLVIMENTO OBITtFICOE TECNOLÓGICO Coordenação Editorial Brasília 1981 VI BRAZILIAN SYMPOSIUM ON THEORETICAL PHYSICS VOLUME III CNPq Comitê Editorial Lynaldo Cavalcanti de Albuquerque José Duarte de Araújo Itiro lida Simon Schwartzman Crodowaldo Pávan Cícero Gontijo Mário Guimarães Ferri Francisco Afonso Biato Brazilian Symposium on Theoretical Physics, 6., Rio de Janeiro 1980. VI Brazilian Symposium on Theoretical Physics. Bra- sília, CNPq, 1981 3v. Bibliografia Conteúdo — v. 1. Nuclear physics, plasma physics and statistical mechanics. — v. 2. Solid state physics, biophy- sics and chemical physics. — v. 3. Relativity and elemen- tary particle physics. 1. Física. 2. Simpósio. I. CNPq. II. Título. CDU 53:061.3(81) FOREWORD The Sixth Brazilian Symposium on Theoretical Physics was held in Rio de Janeiro from 7 to 18 January 1980, consisting in lectures and seminars on topics of current interest to Theoretical Physics. The program covered several branches of modern research, as can be seen in this publication, which presents most of the material discussed in the two weeks of the meeting. The Symposium was held thanks to the generous sponsorship of Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (Brazil), Academia Brasileira de Ciências, Fundação do Amparo a Pesquisas do Estado de . -
Heavy Flavor Physics∗
SLAC{PUB{9551 November 2002 HEAVY FLAVOR PHYSICS∗ Helen R. Quinn Stanford Linear Accelerator Center 2575 Sand Hill Road, Menlo Park, CA 94025 E-mail: [email protected] Abstract These lectures are intended as an introduction to flavor physics for graduate stu- dents in experimental high energy physics. In these four lectures the basic ideas and of the subject and some current issues are presented, but no attempt is made to teach calculational techniques and methods. Lectures given at European School of High-Energy Physics (ESHEP 2002) Pylos, Greece, August 25-September 7, 2002 ∗Work supported by Department of Energy contract DE{AC03{76SF00515. 1 WHAT IS FLAVOR PHYSICS? WHY STUDY IT? The flavor sector is that part of the Standard Model which arises from the interplay of quark weak gauge couplings and quark-Higgs couplings. The Standard Model physics of the quark masses and matrix of quark weak couplings in the mass eigenstate basis that encodes these effects will be briefly reviewed. From a theorist's perspective, the aim of the game in flavor physics today is to search for those places where Standard Model predictions are clean enough that effects from physics from beyond the Stan- dard Model could be recognized if indeed they occur. Along the way we also want to refine our knowledge of the Standard Model parameters of this sector. The Standard Model encodes the physics of weak decays of quarks. Predictions at the quark level are clean and simple, since leading-order weak effects are all we need. However we observe hadrons, not quarks. -
Atoms and Molecules in Intense Laser Fields: Gauge Invariance of Theory and Models
Atoms and Molecules in Intense Laser Fields: Gauge Invariance of Theory and Models A. D. Bandrauk1, F. Fillion-Gourdeau3 and E. Lorin2 1 Laboratoire de chimie th´eorique, Facult´edes Sciences, Universit´ede Sherbrooke, Sherbrooke, Canada, J1K 2R1 2 School of Mathematics & Statistics, Carleton University, Canada, K1S 5B6 3 Centre de Recherches Math´ematiques, Universit´ede Montr´eal,Montr´eal,Canada, H3T 1J4 Abstract. Gauge invariance was discovered in the development of classical electromagnetism and was required when the latter was formulated in terms of scalar and vector potentials. It is now considered to be a fundamental principle of nature, stating that different forms of these potentials yield the same physical description: they describe the same electromagnetic field as long as they are related to each other by gauge transformations. Gauge invariance can also be included into the quantum description of matter interacting with an electromagnetic field by assuming that the wave function transforms under a given local unitary transformation. The result of this procedure is a quantum theory describing the coupling of electrons, nuclei and photons. Therefore, it is a very important concept: it is used in almost every fields of physics and it has been generalized to describe electroweak and strong interactions in the standard model of particles. A review of quantum mechanical gauge invariance and general unitary transformations is presented for atoms and molecules in interaction with intense short laser pulses, spanning the perturbative to highly nonlinear nonperturbative interaction regimes. Various unitary transformations for single spinless particle Time Dependent Schr¨odinger Equations (TDSE) are shown to correspond to different time-dependent Hamiltonians and wave functions. -
Gauge Theory
Preprint typeset in JHEP style - HYPER VERSION 2018 Gauge Theory David Tong Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 OBA, UK http://www.damtp.cam.ac.uk/user/tong/gaugetheory.html [email protected] Contents 0. Introduction 1 1. Topics in Electromagnetism 3 1.1 Magnetic Monopoles 3 1.1.1 Dirac Quantisation 4 1.1.2 A Patchwork of Gauge Fields 6 1.1.3 Monopoles and Angular Momentum 8 1.2 The Theta Term 10 1.2.1 The Topological Insulator 11 1.2.2 A Mirage Monopole 14 1.2.3 The Witten Effect 16 1.2.4 Why θ is Periodic 18 1.2.5 Parity, Time-Reversal and θ = π 21 1.3 Further Reading 22 2. Yang-Mills Theory 26 2.1 Introducing Yang-Mills 26 2.1.1 The Action 29 2.1.2 Gauge Symmetry 31 2.1.3 Wilson Lines and Wilson Loops 33 2.2 The Theta Term 38 2.2.1 Canonical Quantisation of Yang-Mills 40 2.2.2 The Wavefunction and the Chern-Simons Functional 42 2.2.3 Analogies From Quantum Mechanics 47 2.3 Instantons 51 2.3.1 The Self-Dual Yang-Mills Equations 52 2.3.2 Tunnelling: Another Quantum Mechanics Analogy 56 2.3.3 Instanton Contributions to the Path Integral 58 2.4 The Flow to Strong Coupling 61 2.4.1 Anti-Screening and Paramagnetism 65 2.4.2 Computing the Beta Function 67 2.5 Electric Probes 74 2.5.1 Coulomb vs Confining 74 2.5.2 An Analogy: Flux Lines in a Superconductor 78 { 1 { 2.5.3 Wilson Loops Revisited 85 2.6 Magnetic Probes 88 2.6.1 't Hooft Lines 89 2.6.2 SU(N) vs SU(N)=ZN 92 2.6.3 What is the Gauge Group of the Standard Model? 97 2.7 Dynamical Matter 99 2.7.1 The Beta Function Revisited 100 2.7.2 The Infra-Red Phases of QCD-like Theories 102 2.7.3 The Higgs vs Confining Phase 105 2.8 't Hooft-Polyakov Monopoles 109 2.8.1 Monopole Solutions 112 2.8.2 The Witten Effect Again 114 2.9 Further Reading 115 3. -
Early History of Gauge Theories and Kaluza-Klein Theories, With
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server Early History of Gauge Theories and Kaluza-Klein Theories, with a Glance at Recent Developments Lochlain O’Raifeartaigh Dublin Institute for Advanced Studies, Dublin 4, Ireland Norbert Straumann Institut f¨ur Theoretische Physik der Universit¨at Z¨urich–Irchel, Z¨urich, Switzerland Abstract One of the major developments of twentieth century physics has been the gradual recognition that a common feature of the known fundamental inter- actions is their gauge structure. In this article the authors review the early history of gauge theory, from Einstein’s theory of gravitation to the appear- ance of non-abelian gauge theories in the fifties. The authors also review the early history of dimensional reduction, which played an important role in the developement of gauge-theory. A description is given how, in recent times, the ideas of gauge-theory and dimensional reduction have emerged naturally in the context of string theory and non-commutative geometry. Contents I Introduction 1 II Weyl's Attempt to Unify Gravitation and Electromagnetism 6 1 A Weyl’sGeneralizationofRiemannianGeometry............... 6 B ElectromagnetismandGravitation...................... 9 C Einstein’sObjectionandReactionsofOtherPhysicists........... 11 III Weyl's 1929 Classic: \Electron and Gravitation" 15 A TetradFormalism............................... 18 B TheNewFormoftheGauge-Principle.................... 20 IV The Early Work of Kaluza and Klein 23 V Klein's 1938 Theory 31 VI The Pauli Letters to Pais 34 VII Yang-Mills Theory 36 VIII Recent Developments 41 A GaugeTheoryandStrings.......................... 42 1 Introduction................................ 42 2 GaugePropertiesofOpenBosonicStrings................ 43 3 GravitationalPropertiesofClosedBosonicStrings........... 45 4 ThePresenceofMatter.......................... 47 5 Fermionic and Heterotic Strings: Supergravity and Non-Abelian Gauge Theory.................................. -
The Principles of Gauging 2
The Principles of Gauging∗ Holger Lyre†‡ Ruhr-University Bochum The aim of this paper is twofold: First, to present an examination of the principles underlying gauge field theories. I shall argue that there are two principles directly connected to the two well-known theorems of Emmy Noether concerning global and local symmetries of the free matter-field Lagrangian, in the following referred to as “conservation principle” and “gauge principle”. Since both these express nothing but certain symmetry features of the free field theory, they are not sufficient to derive a true interaction coupling to a new gauge field. For this purpose it is necessary to advocate a third, truly empirical principle which may be understood as a generalization of the equivalence principle. The second task of the paper is to deal with the ontological question concerning the reality status of gauge potentials in the light of the proposed logical structure of gauge theories. A nonlocal interpretation of topological effects in gauge theories and, thus, the non-reality of gauge potentials in accordance with the generalized equivalence principle will be favoured. 1. The Gauge Argument. Textbook presentations of the logical structure of gauge field theories usually emphasize the importance of the gauge principle (cf. Aitchison and Hey 1982, µ p. 176): Start with a certain free field theory—take Dirac’s theory LD = ¯(iγ @µ − m) for instance—and consider local gauge transformations (x) → 0(x)=eiqα(x) (x): (1) To satisfy the requirement of local gauge covariance of LD the usual derivative has to be replaced by a covariant derivative @µ → Dµ = @µ − iqAµ: (2) arXiv:quant-ph/0101047 11 Jan 2001 Thus, instead of a free field theory, we obtain—in a somewhat miraculous way—a theory with interaction L →L0 ¯ µ − ¯ µ − ¯ µ D D = (iγ Dµ m) = (iγ @µ m) + qψγ Aµ : (3) Besides this, in usual textbook presentations reference is also made to the importance of “Noether’s theorem”: The existence of a global (i.e. -
Path Integral Approach to Residual Gauge Fixing
Path Integral Approach to Residual Gauge Fixing Ashok Dasa, J. Frenkelb and Silvana Perezc a Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627-0171, USA b Instituto de F´ısica, Universidade de S˜ao Paulo, S˜ao Paulo, BRAZIL and c Departamento de F´ısica, Universidade Federal do Par´a, Bel´em, Par´a66075-110, BRAZIL In this paper we study the question of residual gauge fixing in the path integral approach for a general class of axial-type gauges including the light-cone gauge. We show that the two cases – axial-type gauges and the light-cone gauge – lead to very different structures for the explicit forms of the propagator. In the case of the axial-type gauges, fixing the residual symmetry determines the propagator of the theory completely. On the other hand, in the light-cone gauge there is still a prescription dependence even after fixing the residual gauge symmetry, which is related to the existence of an underlying global symmetry. PACS numbers: 11.15.-q, 11.10.Ef, 12.38.Lg I. INTRODUCTION Light-front field theories [1] have been studied vigorously in the past. Quantization on the light-front (as opposed to equal-time quantization) leads to a larger number of kinematical generators of the Poincar´ealgebra resulting in a trivial vacuum state of the theory [2]. Therefore, non-perturbative calculations can, in principle, be carried out in a simpler manner in such theories. More recently, it has been observed both in the conventional light-front frame as well as in a generalized light-front frame [3, 4, 5] that canonical quantization (within the Hamiltonian formalism) of a gauge theory in the light-cone gauge n A =0, n2 =0, (1) · where Aµ can be thought of as a matrix in the adjoint representation of the gauge group in the case of a non-Abelian theory, leads to a doubly transverse propagator [6, 7].