Solitary Waves in the Nonlinear Dirac Equation
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Dimensional Topological Quantum Field Theory from a Tight-Binding Model of Interacting Spinless Fermions
This is a repository copy of (3+1)-dimensional topological quantum field theory from a tight-binding model of interacting spinless fermions. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/99993/ Version: Accepted Version Article: Cirio, M, Palumbo, G and Pachos, JK (2014) (3+1)-dimensional topological quantum field theory from a tight-binding model of interacting spinless fermions. Physical Review B, 90 (8). 085114. ISSN 2469-9950 https://doi.org/10.1103/PhysRevB.90.085114 Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ (3+1)-dimensional topological quantum field theory from a tight-binding model of interacting spinless fermions Mauro Cirio,1 Giandomenico Palumbo,2 and Jiannis K. Pachos2 1Centre for Engineered Quantum Systems, Department of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109, Australia 2School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom (Dated: July 15, 2014) Currently, there is much interest in discovering analytically tractable (3 + 1)-dimensional models that describe interacting fermions with emerging topological properties. -
What Is the Dirac Equation?
What is the Dirac equation? M. Burak Erdo˘gan ∗ William R. Green y Ebru Toprak z July 15, 2021 at all times, and hence the model needs to be first or- der in time, [Tha92]. In addition, it should conserve In the early part of the 20th century huge advances the L2 norm of solutions. Dirac combined the quan- were made in theoretical physics that have led to tum mechanical notions of energy and momentum vast mathematical developments and exciting open operators E = i~@t, p = −i~rx with the relativis- 2 2 2 problems. Einstein's development of relativistic the- tic Pythagorean energy relation E = (cp) + (E0) 2 ory in the first decade was followed by Schr¨odinger's where E0 = mc is the rest energy. quantum mechanical theory in 1925. Einstein's the- Inserting the energy and momentum operators into ory could be used to describe bodies moving at great the energy relation leads to a Klein{Gordon equation speeds, while Schr¨odinger'stheory described the evo- 2 2 2 4 lution of very small particles. Both models break −~ tt = (−~ ∆x + m c ) : down when attempting to describe the evolution of The Klein{Gordon equation is second order, and does small particles moving at great speeds. In 1927, Paul not have an L2-conservation law. To remedy these Dirac sought to reconcile these theories and intro- shortcomings, Dirac sought to develop an operator1 duced the Dirac equation to describe relativitistic quantum mechanics. 2 Dm = −ic~α1@x1 − ic~α2@x2 − ic~α3@x3 + mc β Dirac's formulation of a hyperbolic system of par- tial differential equations has provided fundamental which could formally act as a square root of the Klein- 2 2 2 models and insights in a variety of fields from parti- Gordon operator, that is, satisfy Dm = −c ~ ∆ + 2 4 cle physics and quantum field theory to more recent m c . -
Dirac Equation - Wikipedia
Dirac equation - Wikipedia https://en.wikipedia.org/wiki/Dirac_equation Dirac equation From Wikipedia, the free encyclopedia In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. In its free form, or including electromagnetic interactions, it 1 describes all spin-2 massive particles such as electrons and quarks for which parity is a symmetry. It is consistent with both the principles of quantum mechanics and the theory of special relativity,[1] and was the first theory to account fully for special relativity in the context of quantum mechanics. It was validated by accounting for the fine details of the hydrogen spectrum in a completely rigorous way. The equation also implied the existence of a new form of matter, antimatter, previously unsuspected and unobserved and which was experimentally confirmed several years later. It also provided a theoretical justification for the introduction of several component wave functions in Pauli's phenomenological theory of spin; the wave functions in the Dirac theory are vectors of four complex numbers (known as bispinors), two of which resemble the Pauli wavefunction in the non-relativistic limit, in contrast to the Schrödinger equation which described wave functions of only one complex value. Moreover, in the limit of zero mass, the Dirac equation reduces to the Weyl equation. Although Dirac did not at first fully appreciate the importance of his results, the entailed explanation of spin as a consequence of the union of quantum mechanics and relativity—and the eventual discovery of the positron—represents one of the great triumphs of theoretical physics. -
Transverse Instability of Line Solitary Waves in Massive Dirac Equations
J Nonlinear Sci (2016) 26:365–403 DOI 10.1007/s00332-015-9278-1 Transverse Instability of Line Solitary Waves in Massive Dirac Equations Dmitry Pelinovsky1 · Yusuke Shimabukuro1 Received: 7 November 2014 / Accepted: 23 October 2015 / Published online: 6 November 2015 © Springer Science+Business Media New York 2015 Abstract Working in the context of localized modes in periodic potentials, we con- sider two systems of the massive Dirac equations in two spatial dimensions. The first system, a generalized massive Thirring model, is derived for the periodic stripe poten- tials. The second one, a generalized massive Gross–Neveu equation, is derived for the hexagonal potentials. In both cases, we prove analytically that the line solitary waves are spectrally unstable with respect to periodic transverse perturbations of large periods. The spectral instability is induced by the spatial translation for the general- ized massive Thirring model and by the gauge rotation for the generalized massive Gross–Neveu model. We also observe numerically that the spectral instability holds for the transverse perturbations of any period in the generalized massive Thirring model and exhibits a finite threshold on the period of the transverse perturbations in the generalized massive Gross–Neveu model. Keywords Massive Thirring model · Massive Gross-Neveu equation · Line solitary waves · Transverse instability · Lyapunov-Schmidt reduction method · Chebyshev interpolation method Mathematics Subject Classification 35Q41 · 37K40 · 37K45 Communicated by Michael I. Weinstein. B Dmitry Pelinovsky [email protected] 1 Department of Mathematics and Statistics, McMaster University, Hamilton, ON L8S 4K1, Canada 123 366 J Nonlinear Sci (2016) 26:365–403 1 Introduction Starting with pioneer contributions of V.E. -
Ivanenko. Biography
The People of Physics Faculty Selected papers of the Journal “Soviet Physicist” 1998-2006 Dmitri Ivanenko. Scientific Biography 226 Dmitri Ivanenko (29.07.1904 - 30.12.1994), professor of Moscow State University (since 1943) , was one of the great theoreticians of XX century. He made the fundamental contribution to many areas of nuclear physics, field theory and gravitation theory. His outstanding achievements include: • The Fock - Ivanenko coefficients of parallel displacement of spinors in a curved space-time (1929) 1 . Nobel laureate Abdus Salam called it the first gauge theory. • The Ambartsumian - Ivanenko hypothesis of creation of massive particles which is a corner stone of contemporary quantum field theory (1930) 2 . • The proton-neutron model of atomic nuclei (1932) 3 . • The first shell model of nuclei (in collaboration with E. Gapon) (1932) 4 . • The first model of exchange nuclear forces by means of massive particles (in collaboration with I. Tamm) (1934) 5 . Based on this model, Nobel laureate H. Yukawa developed his meson theory. • The prediction of synchrotron radiation (in collaboration with I. Pomeranchuk) (1944) 6 and its classical theory (in collaboration with A. Sokolov). • Theory of hypernucleus (1956) 7 . • The hypothesis of quark stars (in collaboration with D. Kurdgelaidze) (1965) 8 . • The gauge gravitation theory (in collaboration with G. Sardanashvily), where gravity is treated as a Higgs field responsible for spontaneous breaking of space- 9 time symmetries (1983) . References 1. Fock V., Iwanenko D., Géometrie quantique linéaire et déplacement paralléle, Compt. Rend. Acad Sci. Paris 188 (1929) 1470. 2. Ambarzumian V., Iwanenko D., Les électrons inobservables et les rayons, Compt. -
Lecture 9 Sine-Gordon Model and Thirring Model Consider the Action
Lecture 9 Sine-Gordon model and Thirring model Consider the action of the sine-Gordon model in the general form Z (@ ')2 S ['] = d2x µ + 2µ cos β' : (1) sG 16π Here the action depends on two parameters: β and µ. Thep parameter β is dimensionless. We may consider it as the square root of the Planck constant: β = ~. Indeed, let u(x) = β'(x). Then the action is 1 Z (@ u)2 S = d2x µ + 2µβ2 cos u : sG β2 16π For β 1 the square of mass of the lightest excitation is m2 = 16πµβ2. If we keep it finite, the only place β enters is the prefactor, which must be ~−1 in the quantum case. We will consider the sine-Gordon theory as a perturbation of a free massless boson. The perturbation operator :cos β': has the scaling dimension 2β2. Hence, the dimension of the parameter µ is 2 − 2β2. Since this is the only dimensional parameter, masses of all particles in the theory must be proportional 2 to µ1=(2−2β ). In the limit β ! 0 we have m / µ1=2 as expected. The behavior of the model depends of the value of β. There are three cases 1. β2 < 1. The dimension of µ is positive, the perturbation is relevant. It means that the interaction decreases with decreasing scale. The short-range correlation functions behave like those in the massless free field theory. It makes the sine-Gordon theory well-defined and superrenormalizable. But the large-distance behavior strikingly differs from the short-distance one. It is described by a system of massive particles, whose mass spectrum essentially depends on the parameter β. -
International Centre for Theoretical Physics
INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS OUTLINE OF A NONLINEAR, RELATIVISTIC QUANTUM MECHANICS OF EXTENDED PARTICLES Eckehard W. Mielke INTERNATIONAL ATOMIC ENERGY AGENCY UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION 1981 MIRAMARE-TRIESTE IC/81/9 International Atomic Energy Agency and United Nations Educational Scientific and Cultural Organization 3TERKATIOHAL CENTRE FOR THEORETICAL PHTSICS OUTLINE OF A NONLINEAR, KELATIVXSTTC QUANTUM HECHAHICS OF EXTENDED PARTICLES* Eckehard W. Mielke International Centre for Theoretical Physics, Trieste, Italy. MIRAHABE - TRIESTE January 198l • Submitted for publication. ABSTRACT I. INTRODUCTION AMD MOTIVATION A quantum theory of intrinsically extended particles similar to de Broglie's In recent years the conviction has apparently increased among most theory of the Double Solution is proposed, A rational notion of the particle's physicists that all fundamental interactions between particles - including extension is enthroned by realizing its internal structure via soliton-type gravity - can be comprehended by appropriate extensions of local gauge theories. solutions of nonlinear, relativistic wave equations. These droplet-type waves The principle of gauge invarisince was first formulated in have a quasi-objective character except for certain boundary conditions vhich 1923 by Hermann Weyl[l57] with the aim to give a proper connection between may be subject to stochastic fluctuations. More precisely, this assumption Dirac's relativistic quantum theory [37] of the electron and the Maxwell- amounts to a probabilistic description of the center of a soliton such that it Lorentz's theory of electromagnetism. Later Yang and Mills [167] as well as would follow the conventional quantum-mechanical formalism in the limit of zero Sharp were able to extend the latter theory to a nonabelian gauge particle radius. -
Unified Equations of Boson and Fermion at High Energy and Some
Unified Equations of Boson and Fermion at High Energy and Some Unifications in Particle Physics Yi-Fang Chang Department of Physics, Yunnan University, Kunming, 650091, China (e-mail: [email protected]) Abstract: We suggest some possible approaches of the unified equations of boson and fermion, which correspond to the unified statistics at high energy. A. The spin terms of equations can be neglected. B. The mass terms of equations can be neglected. C. The known equations of formal unification change to the same. They can be combined each other. We derive the chaos solution of the nonlinear equation, in which the chaos point should be a unified scale. Moreover, various unifications in particle physics are discussed. It includes the unifications of interactions and the unified collision cross sections, which at high energy trend toward constant and rise as energy increases. Key words: particle, unification, equation, boson, fermion, high energy, collision, interaction PACS: 12.10.-g; 11.10.Lm; 12.90.+b; 12.10.Dm 1. Introduction Various unifications are all very important questions in particle physics. In 1930 Band discussed a new relativity unified field theory and wave mechanics [1,2]. Then Rojansky researched the possibility of a unified interpretation of electrons and protons [3]. By the extended Maxwell-Lorentz equations to five dimensions, Corben showed a simple unified field theory of gravitational and electromagnetic phenomena [4,5]. Hoffmann proposed the projective relativity, which is led to a formal unification of the gravitational and electromagnetic fields of the general relativity, and yields field equations unifying the gravitational and vector meson fields [6]. -
The Nonlinear Dirac Equation in Bose-Einstein Condensates
The Nonlinear Dirac Equation in Bose-Einstein Condensates: Foundation and Symmetries L. H. Haddad and L. D. Carr Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA Abstract We show that Bose-Einstein condensates in a honeycomb optical lattice are described by a nonlinear Dirac equation in the long wavelength, mean field limit. Unlike nonlinear Dirac equations posited by particle theorists, which are designed to preserve the principle of relativity, i.e., Poincar´ecovariance, the nonlinear Dirac equation for Bose-Einstein condensates breaks this symmetry. We present a rigorous derivation of the nonlinear Dirac equation from first principles. We provide a thorough discussion of all symmetries broken and maintained. Key words: Nonlinear Dirac equation, Nonlinear Schrodinger equation, Bose-Einstein condensates, Ultra-cold atoms, Optical lattices, Graphene PACS: 05.45.-a, 03.75.-b, 67.85.Hj 1. Introduction perature and interaction sign, magnitude, and symmetry can be controlled externally. Moreover, 2D physics has Recently the first truly two-dimensional (2D) solid state recently been of great interest in this context, in the form material, graphene, was created in the laboratory [1,2]. One of the Berzinskii-Kosterlitz-Thouless crossover [5], and 2D of the most exciting aspects of this novel material is that systems underpinned by lattices are immediately available long wavelength excitations are described by a Dirac equa- in experiments. Instead of considering ultra-cold fermions, tion for massless particles, with a “speed of light” equal to which could be used to produce an near-exact analog of the Fermi velocity vF c/300 [3]. Thus one can study rela- graphene [6], we consider ultra-cold bosons. -
Effective Field Theories for Interacting Boundaries of 3D Topological
www.nature.com/scientificreports OPEN Efective feld theories for interacting boundaries of 3D topological crystalline insulators through bosonisation Patricio Salgado‑Rebolledo1*, Giandomenico Palumbo2 & Jiannis K. Pachos1 Here, we analyse two Dirac fermion species in two spatial dimensions in the presence of general quartic contact interactions. By employing functional bosonisation techniques, we demonstrate that depending on the couplings of the fermion interactions the system can be efectively described by a rich variety of topologically massive gauge theories. Among these efective theories, we obtain an extended Chern–Simons theory with higher order derivatives as well as two coupled Chern–Simons theories. Our formalism allows for a general description of interacting fermions emerging, for example, at the gapped boundary of three‑dimensional topological crystalline insulators. Time-reversal-invariant topological insulators are among the most well studied topological phases of matter. In three dimensions, they are characterised by suitable topological numbers in the bulk that guarantee the existence 1,2 of topologically protected massless Dirac fermions on the boundary . Although the topological invariant is a Z2 number, on the slab geometry, it has been shown that robust surface states are given by an odd number of Dirac fermions per boundary3. Te situation changes in the case of three-dimensional topological crystalline insula- tors (TCIs), namely topological insulators characterised by further crystalline symmetries, such as mirror and rotation symmetries4–11. In particular, for three-dimensional TCIs protected by a single mirror symmetry, one can defne the so called mirror Chern number nM on a given two-dimensional plane, which is invariant under 5 the mirror symmetry. -
VARIATIONAL ANALYSIS of the THIRRING MODEL* Sidney
SLAC-PUB-1999 August 1977 (T) FERMION FIELD THEORY ON A LATTICE: VARIATIONAL ANALYSIS OF THE THIRRING MODEL* Sidney D. Drell, Benjamin Svetitsky**, and Marvin Weinstein Stanford Linear Accelerator Center Stanford University, Stanford, California 94305 Abstract We extend variational techniques previously described to study the two-dimensional massless free fermion field and the Thirring model on a spatial lattice, The iterative block spin procedure of con- structing an effective lattice Hamiltonian, starting ,by dissecting the lattice into Z-site blocks, is shown to be successful in producing results known for the continuum Thirring model. Submitted to Phys . Rev. *Work supported by the Energy Research and Development Administration, **National Science Foundation Graduate Fellow in absentia from Princeton University. -2- 1. INTRODUCTION I,n this paper we continue the development and application of techniques for finding the ground state and spectrum of low-lying physical states of field the- ories without recourse to either weak or strong coupling expansioas. Following 1 our earlier papers we study lattice Hamiltonians by means of a constructive variational procedure. The methods, which in our preceding paper (Paper III) were described and applied to free field theory of bosons in oae space dimension and to the one-dimensional Ising model with a transverse applied mag.netic field, are now applied to two fermion theories in lx - It dimensions: massless free 2-5 fermions and the Thirring .model. Our aim in this paper is to demonstrate that these methods are easily applied to fermion theories and that our simple con- structive approach reproduces results known to hold in soluble continuum models. -
AN OVERVIEW on LINEAR and NONLINEAR DIRAC EQUATIONS 1. Introduction and Basic Properties of the Dirac Operator. in Relativistic
DISCRETE AND CONTINUOUS Website: http://AIMsciences.org DYNAMICAL SYSTEMS Volume 8, Number 2, April 2002 pp. 381–397 AN OVERVIEW ON LINEAR AND NONLINEAR DIRAC EQUATIONS MARIA J. ESTEBAN AND ERIC SER´ E´ Abstract. In this paper we review the variational treatment of linear and nonlinear eigenvalue problems involving the Dirac operator. These problems arise when searching for bound states and bound energies of electrons sub- mitted to external or self-consistent interactions in a relativistic framework. The corresponding energy functionals are totally indefinite and that creates difficulties to define variational principles related to those equations. Here we describe recent works dealing with this kind of problems. In particular we describe the solutions found to linear Dirac equations with external potential, the Maxwell-Dirac equations, some nonlinear Dirac equations with local non- linear terms and the Dirac-Fock equations arising in the description of atoms and molecules. 1. Introduction and basic properties of the dirac operator. In relativistic quantum mechanics [11], the state of a free electron is represented by a wave func- tion Ψ(t, x) with Ψ(t, .) ∈ L2(IR3, CI 4) for any t. This wave satisfies the free Dirac equation: 3 X 2 i ∂t Ψ = H0Ψ, with H0 = −ic~ αk∂k + mc β, (1.1) k=1 where c denotes the speed of light, m > 0, the mass of the electron, and ~ is Planck’s constant. In the Dirac equation, α1, α2, α3 and β are 4×4 complex matrices, whose standard form (in 2 × 2 blocks) is I 0 0 σk β = , αk = (k = 1, 2, 3), 0 −I σk 0 with 0 1 0 −i 1 0 σ = , σ = , σ = .