Wave Equations Greiner Greiner Quantum Mechanics Mechanics I an Introduction 3Rd Edition (In Preparation)
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The Zig-Zag Road to Reality 1 Introduction
The zig-zag road to reality Author Colin, S, Wiseman, HM Published 2011 Journal Title Journal of Physics A: Mathematical and Theoretical DOI https://doi.org/10.1088/1751-8113/44/34/345304 Copyright Statement © 2011 Institute of Physics Publishing. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher.Please refer to the journal's website for access to the definitive, published version. Downloaded from http://hdl.handle.net/10072/42701 Griffith Research Online https://research-repository.griffith.edu.au The zig-zag road to reality S Colin1;2;y and H M Wiseman1;z 1 Centre for Quantum Dynamics, Griffith University, Brisbane, QLD 4111, Australia. 2 Perimeter Institute for Theoretical Physics, 31 Caroline Street North, ON N2L2Y5, Waterloo, Canada. E-mail: [email protected], [email protected] Abstract In the standard model of particle physics, all fermions are fundamentally massless and only acquire their effective bare mass when the Higgs field condenses. Therefore, in a fundamental de Broglie-Bohm pilot-wave quan- tum field theory (valid before and after the Higgs condensation), position beables should be attributed to massless fermions. In our endeavour to build a pilot-wave theory of massless fermions, which would be relevant for the study of quantum non-equilibrium in the early universe, we are naturally led to Weyl spinors and to particle trajectories which give mean- ing to the `zig-zag' picture of the electron discussed recently by Penrose. We show that a positive-energy massive Dirac electron of given helicity can be thought of as a superposition of positive and negative energy Weyl particles of the same helicity and that a single massive Dirac electron can in principle move luminally at all times. -
1 Introduction 2 Klein Gordon Equation
Thimo Preis 1 1 Introduction Non-relativistic quantum mechanics refers to the mathematical formulation of quantum mechanics applied in the context of Galilean relativity, more specifically quantizing the equations from the Hamiltonian formalism of non-relativistic Classical Mechanics by replacing dynamical variables by operators through the correspondence principle. Therefore, the physical properties predicted by the Schrödinger theory are invariant in a Galilean change of referential, but they do not have the invariance under a Lorentz change of referential required by the principle of relativity. In particular, all phenomena concerning the interaction between light and matter, such as emission, absorption or scattering of photons, is outside the framework of non-relativistic Quantum Mechanics. One of the main difficulties in elaborating relativistic Quantum Mechanics comes from the fact that the law of conservation of the number of particles ceases in general to be true. Due to the equivalence of mass and energy there can be creation or absorption of particles whenever the interactions give rise to energy transfers equal or superior to the rest massses of these particles. This theory, which i am about to present to you, is not exempt of difficulties, but it accounts for a very large body of experimental facts. We will base our deductions upon the six axioms of the Copenhagen Interpretation of quantum mechanics.Therefore, with the principles of quantum mechanics and of relativistic invariance at our disposal we will try to construct a Lorentz covariant wave equation. For this we need special relativity. 1.1 Special Relativity Special relativity states that the laws of nature are independent of the observer´s frame if it belongs to the class of frames obtained from each other by transformations of the Poincaré group. -
Some Remarks About Mass and Zitterbewegung Substructure Of
Some remarks about mass and Zitterbewegung substructure of electron P. Brovetto†, V. Maxia† and M. Salis†‡ (1) †On leave from Istituto Nazionale di Fisica della Materia - Cagliari, Italy ‡Dipartimento di Fisica - Universit`adi Cagliari, Italy Abstract - It is shown that the electron Zitterbewegung, that is, the high- frequency microscopic oscillatory motion of electron about its centre of mass, originates a spatial distribution of charge. This allows the point-like electron behave like a particle of definite size whose self-energy, that is, energy of its electromagnetic field, owns a finite value. This has implications for the electron mass, which, in principle, might be derived from Zitterbewegung physics. Key words - Elementary particle masses, Zitterbewegung theory. Introduction The nature of mass of elementary particles is one of the most intriguing top- ics in modern physics. Electron deserves a special attention because, differently from quarks which are bound in composite objects (adrons), it is a free parti- cle. Moreover, differently from neutrinos whose vanishingly small mass is still controversial, its mass is a well-known quantity. At the beginning of the past century, the question of the nature of elec- tron mass was debated on the ground of the electromagnetic theory by various authors (Abraham, Lorentz, Poincar´e). Actually, the electron charge e origi- nates in the surrounding space an electromagnetic field −→E, −→H, associated with energy density E2 + H2 /8π and momentum density −→E −→H /4πc. These × densities, when integrated over the space, account for electron self-energy and inertial mass. However, peculiar models must be introduced in order to avoid divergent results. -
Effective Field Theories, Reductionism and Scientific Explanation Stephan
To appear in: Studies in History and Philosophy of Modern Physics Effective Field Theories, Reductionism and Scientific Explanation Stephan Hartmann∗ Abstract Effective field theories have been a very popular tool in quantum physics for almost two decades. And there are good reasons for this. I will argue that effec- tive field theories share many of the advantages of both fundamental theories and phenomenological models, while avoiding their respective shortcomings. They are, for example, flexible enough to cover a wide range of phenomena, and concrete enough to provide a detailed story of the specific mechanisms at work at a given energy scale. So will all of physics eventually converge on effective field theories? This paper argues that good scientific research can be characterised by a fruitful interaction between fundamental theories, phenomenological models and effective field theories. All of them have their appropriate functions in the research process, and all of them are indispens- able. They complement each other and hang together in a coherent way which I shall characterise in some detail. To illustrate all this I will present a case study from nuclear and particle physics. The resulting view about scientific theorising is inherently pluralistic, and has implications for the debates about reductionism and scientific explanation. Keywords: Effective Field Theory; Quantum Field Theory; Renormalisation; Reductionism; Explanation; Pluralism. ∗Center for Philosophy of Science, University of Pittsburgh, 817 Cathedral of Learning, Pitts- burgh, PA 15260, USA (e-mail: [email protected]) (correspondence address); and Sektion Physik, Universit¨at M¨unchen, Theresienstr. 37, 80333 M¨unchen, Germany. 1 1 Introduction There is little doubt that effective field theories are nowadays a very popular tool in quantum physics. -
Casimir Effect on the Lattice: U (1) Gauge Theory in Two Spatial Dimensions
Casimir effect on the lattice: U(1) gauge theory in two spatial dimensions M. N. Chernodub,1, 2, 3 V. A. Goy,4, 2 and A. V. Molochkov2 1Laboratoire de Math´ematiques et Physique Th´eoriqueUMR 7350, Universit´ede Tours, 37200 France 2Soft Matter Physics Laboratory, Far Eastern Federal University, Sukhanova 8, Vladivostok, 690950, Russia 3Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent, Belgium 4School of Natural Sciences, Far Eastern Federal University, Sukhanova 8, Vladivostok, 690950, Russia (Dated: September 8, 2016) We propose a general numerical method to study the Casimir effect in lattice gauge theories. We illustrate the method by calculating the energy density of zero-point fluctuations around two parallel wires of finite static permittivity in Abelian gauge theory in two spatial dimensions. We discuss various subtle issues related to the lattice formulation of the problem and show how they can successfully be resolved. Finally, we calculate the Casimir potential between the wires of a fixed permittivity, extrapolate our results to the limit of ideally conducting wires and demonstrate excellent agreement with a known theoretical result. I. INTRODUCTION lattice discretization) described by spatially-anisotropic and space-dependent static permittivities "(x) and per- meabilities µ(x) at zero and finite temperature in theories The influence of the physical objects on zero-point with various gauge groups. (vacuum) fluctuations is generally known as the Casimir The structure of the paper is as follows. In Sect. II effect [1{3]. The simplest example of the Casimir effect is we review the implementation of the Casimir boundary a modification of the vacuum energy of electromagnetic conditions for ideal conductors and propose its natural field by closely-spaced and perfectly-conducting parallel counterpart in the lattice gauge theory. -
1 the LOCALIZED QUANTUM VACUUM FIELD D. Dragoman
1 THE LOCALIZED QUANTUM VACUUM FIELD D. Dragoman – Univ. Bucharest, Physics Dept., P.O. Box MG-11, 077125 Bucharest, Romania, e-mail: [email protected] ABSTRACT A model for the localized quantum vacuum is proposed in which the zero-point energy of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated to the zero-point energy of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift; it also offers a new insight into the Zitterbewegung of material particles. 2 INTRODUCTION The zero-point energy (ZPE) of the quantum electromagnetic field is at the same time an indispensable concept of quantum field theory and a controversial issue (see [1] for an excellent review of the subject). The need of the ZPE has been recognized from the beginning of quantum theory of radiation, since only the inclusion of this term assures no first-order temperature-independent correction to the average energy of an oscillator in thermal equilibrium with blackbody radiation in the classical limit of high temperatures. A more rigorous introduction of the ZPE stems from the treatment of the electromagnetic radiation as an ensemble of harmonic quantum oscillators. Then, the total energy of the quantum electromagnetic field is given by E = åk,s hwk (nks +1/ 2) , where nks is the number of quantum oscillators (photons) in the (k,s) mode that propagate with wavevector k and frequency wk =| k | c = kc , and are characterized by the polarization index s. -
Zitterbewegung and a Formulation for Quantum Mechanics
Zitterbewegung and a formulation for quantum mechanics B. G. Sidharth∗ and Abhishek Das† B.M. Birla Science Centre, Adarsh Nagar, Hyderabad - 500 063, India Abstract In this short note, we try to show that inside a vortex like region, like a black hole one cane observe superluminosity which yields some interesting results. Also, we consider the zitterbewegung fluctuations to obtain an interpretation of quantum mechanics. 1 Introduction As is well known, the phenomenon of zitterbewegung has been studied by many eminent authors like Schrodinger [1] and Dirac [2]. Zitterbewegung is a type of rapid fluctuation that is attributed to the interference between positive and negative energy states. Dirac pointed out that the rapidly oscillating terms that arise on account of zitterbewegung is averaged out when we take a measurement remembering that no measurement is instanta- neous. Interestingly, Hestenes [3, 4] too sought to explain quantum mechanics through the phe- nomenon of zitterbewegung. Besides, the authors of this paper have also studied the afore- said phenomenon quite extensively in the past few years [5, 6, 7, 8, 9, 10]. However, in this paper we shall derive some interesting results that substantiate that the Compton scale and zitterbewegung can delineate several phenomena. 2 Theory arXiv:2002.11463v1 [physics.gen-ph] 8 Feb 2020 Let us consider an object, such as a black hole or some particle, that is spiralling like a vortex. In that case, we know that the circulation is given by 2π~n Γ = vdr = ¼C m ∗Email: [email protected] †Email: [email protected] 1 where, C denotes the contour of the vortex, n is the number of turns and m is the mass of the circulating particle. -
2 Lecture 1: Spinors, Their Properties and Spinor Prodcuts
2 Lecture 1: spinors, their properties and spinor prodcuts Consider a theory of a single massless Dirac fermion . The Lagrangian is = ¯ i@ˆ . (2.1) L ⇣ ⌘ The Dirac equation is i@ˆ =0, (2.2) which, in momentum space becomes pUˆ (p)=0, pVˆ (p)=0, (2.3) depending on whether we take positive-energy(particle) or negative-energy (anti-particle) solutions of the Dirac equation. Therefore, in the massless case no di↵erence appears in equations for paprticles and anti-particles. Finding one solution is therefore sufficient. The algebra is simplified if we take γ matrices in Weyl repreentation where µ µ 0 σ γ = µ . (2.4) " σ¯ 0 # and σµ =(1,~σ) andσ ¯µ =(1, ~ ). The Pauli matrices are − 01 0 i 10 σ = ,σ= − ,σ= . (2.5) 1 10 2 i 0 3 0 1 " # " # " − # The matrix γ5 is taken to be 10 γ5 = − . (2.6) " 01# We can use the matrix γ5 to construct projection operators on to upper and lower parts of the four-component spinors U and V . The projection operators are 1 γ 1+γ Pˆ = − 5 , Pˆ = 5 . (2.7) L 2 R 2 Let us write u (p) U(p)= L , (2.8) uR(p) ! where uL(p) and uR(p) are two-component spinors. Since µ 0 pµσ pˆ = µ , (2.9) " pµσ¯ 0(p) # andpU ˆ (p) = 0, the two-component spinors satisfy the following (Weyl) equations µ µ pµσ uR(p)=0,pµσ¯ uL(p)=0. (2.10) –3– Suppose that we have a left handed spinor uL(p) that satisfies the Weyl equation. -
Pilot-Wave Hydrodynamics
FL47CH12-Bush ARI 1 December 2014 20:26 Pilot-Wave Hydrodynamics John W.M. Bush Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; email: [email protected] Annu. Rev. Fluid Mech. 2015. 47:269–92 Keywords First published online as a Review in Advance on walking drops, Faraday waves, quantum analogs September 10, 2014 The Annual Review of Fluid Mechanics is online at Abstract fluid.annualreviews.org Yves Couder, Emmanuel Fort, and coworkers recently discovered that a This article’s doi: millimetric droplet sustained on the surface of a vibrating fluid bath may 10.1146/annurev-fluid-010814-014506 self-propel through a resonant interaction with its own wave field. This ar- Copyright c 2015 by Annual Reviews. ticle reviews experimental evidence indicating that the walking droplets ex- All rights reserved hibit certain features previously thought to be exclusive to the microscopic, Annu. Rev. Fluid Mech. 2015.47:269-292. Downloaded from www.annualreviews.org quantum realm. It then reviews theoretical descriptions of this hydrody- namic pilot-wave system that yield insight into the origins of its quantum- Access provided by Massachusetts Institute of Technology (MIT) on 01/07/15. For personal use only. like behavior. Quantization arises from the dynamic constraint imposed on the droplet by its pilot-wave field, and multimodal statistics appear to be a feature of chaotic pilot-wave dynamics. I attempt to assess the po- tential and limitations of this hydrodynamic system as a quantum analog. This fluid system is compared to quantum pilot-wave theories, shown to be markedly different from Bohmian mechanics and more closely related to de Broglie’s original conception of quantum dynamics, his double-solution theory, and its relatively recent extensions through researchers in stochastic electrodynamics. -
Can Gravitons Be Effectively Massive Due to Their Zitterbewegung Motion? Elias Koorambas
Can gravitons be effectively massive due to their zitterbewegung motion? Elias Koorambas To cite this version: Elias Koorambas. Can gravitons be effectively massive due to their zitterbewegung motion?. 2014. hal-00990723 HAL Id: hal-00990723 https://hal.archives-ouvertes.fr/hal-00990723 Preprint submitted on 14 May 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Can gravitons be effectively massive due to their zitterbewegung motion? E.Koorambas 8A Chatzikosta, 11521 Ampelokipi, Athens, Greece E-mail:[email protected] Submission Date: May 14, 2014 Abstract: Following up on an earlier, De Broglie-Bohm approach within the framework of quantum gauge theory of gravity, and based on the Schrödinger-Dirac equation for gravitons, we argue that gravitons are effectively massive due to their localized circulatory motion. This motion is analogous to the proposed zitterbewegung (ZB) motion of electrons. PACS numbers: 04.60.-m, 11.15.-q, 03.65.Ta Keywords: Quantum Gravity, Gauge Field, Bohm Potential, Zitterbewegung Model 1. Introduction Following, D. Hestenes, the idea that the The ZB of photons is studied via the electron spin and magnetic moment are momentum vector of the electromagnetic generated by a localized circulatory motion of field. -
Lectures on Effective Field Theories
Adam Falkowski Lectures on Effective Field Theories Version of September 21, 2020 Abstract Effective field theories (EFTs) are widely used in particle physics and well beyond. The basic idea is to approximate a physical system by integrating out the degrees of freedom that are not relevant in a given experimental setting. These are traded for a set of effective interactions between the remaining degrees of freedom. In these lectures I review the concept, techniques, and applications of the EFT framework. The 1st lecture gives an overview of the EFT landscape. I will review the philosophy, basic techniques, and applications of EFTs. A few prominent examples, such as the Fermi theory, the Euler-Heisenberg Lagrangian, and the SMEFT, are presented to illustrate some salient features of the EFT. In the 2nd lecture I discuss quantitatively the procedure of integrating out heavy particles in a quantum field theory. An explicit example of the tree- and one-loop level matching between an EFT and its UV completion will be discussed in all gory details. The 3rd lecture is devoted to path integral methods of calculating effective Lagrangians. Finally, in the 4th lecture I discuss the EFT approach to constraining new physics beyond the Standard Model (SM). To this end, the so- called SM EFT is introduced, where the SM Lagrangian is extended by a set of non- renormalizable interactions representing the effects of new heavy particles. 1 Contents 1 Illustrated philosophy of EFT3 1.1 Introduction..................................3 1.2 Scaling and power counting.........................6 1.3 Illustration #1: Fermi theory........................8 1.4 Illustration #2: Euler-Heisenberg Lagrangian.............. -
Gauge Theories in Particle Physics
GRADUATE STUDENT SERIES IN PHYSICS Series Editor: Professor Douglas F Brewer, MA, DPhil Emeritus Professor of Experimental Physics, University of Sussex GAUGE THEORIES IN PARTICLE PHYSICS A PRACTICAL INTRODUCTION THIRD EDITION Volume 1 From Relativistic Quantum Mechanics to QED IAN J R AITCHISON Department of Physics University of Oxford ANTHONY J G HEY Department of Electronics and Computer Science University of Southampton CONTENTS Preface to the Third Edition xiii PART 1 INTRODUCTORY SURVEY, ELECTROMAGNETISM AS A GAUGE THEORY, AND RELATIVISTIC QUANTUM MECHANICS 1 Quarks and Leptons 3 1.1 The Standard Model 3 1.2 Levels of structure: from atoms to quarks 5 1.2.1 Atoms ---> nucleus 5 1.2.2 Nuclei -+ nucleons 8 1.2.3 . Nucleons ---> quarks 12 1.3 The generations and flavours of quarks and leptons 18 1.3.1 Lepton flavour 18 1.3.2 Quark flavour 21 2 Partiele Interactions in the Standard Model 28 2.1 Introduction 28 2.2 The Yukawa theory of force as virtual quantum exchange 30 2.3 The one-quantum exchange amplitude 34 2.4 Electromagnetic interactions 35 2.5 Weak interactions 37 2.6 Strong interactions 40 2.7 Gravitational interactions 44 2.8 Summary 48 Problems 49 3 Eleetrornagnetism as a Gauge Theory 53 3.1 Introduction 53 3.2 The Maxwell equations: current conservation 54 3.3 The Maxwell equations: Lorentz covariance and gauge invariance 56 3.4 Gauge invariance (and covariance) in quantum mechanics 60 3.5 The argument reversed: the gauge principle 63 3.6 Comments an the gauge principle in electromagnetism 67 Problems 73 viii CONTENTS 4