DOCSLIB.ORG

Chapter 1 Vectors and Tensors

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chapter 1 Vectors and Tensors Chapter 1 Vectors and tensors 1.1 Books and links The main text for the course is AM Steane, Relativity Made Relatively Easy (OUP, 2012). Additional details can be found in JD Jackson's Classical Electrodynamics. The webpage for the course can be found at http://www-pnp.physics.ox.ac.uk/ tseng/teaching/b2/. The page includes problem sets, links to related courses and materials, and old lecture notes with detailed derivations. The old lecture notes follow the older syllabus, so in some areas contain material which is beyond the current course 1.2 Postulates of Special Relativity 1. Principle of Relativity (two versions): • Laws of physics take the same mathematical form in all inertial frames of reference. • Motion of bodies in a given space are the same among themselves, whether the space is at rest or moving uniformly. 2. Light speed postulate: there is a maximum speed for signals. 3. Space dimensions are flat (\Euclidean") 1.3 Vectors A point is used in two ways: • geometrically, it's a location, independent of how the location is described; 3 B2: Symmetry and Relativity J Tseng • a set of N variables (coordinates which describe a location, conventionally x1; x2; ··· xN The superscript is also by convention (not an exponent). A coordinate system is a mapping between sets of coordinates and the geometric locations. The sets form an N-dimensional vector space. We typically expect that the laws of physics shouldn't depend on the choice of coordinate system. Note that we are using the word \location" in a broad sense: it can be a spatial location, but if combined with a time coordinate, it's a spacetime point, sometimes called an event. A coordinate transformation is a set of N functions of xi xi = xi(x1; x2; ··· xN ) The transformation is usually invertible. A contravariant vector field is a set of N functions of xi Ai = Ai(x1; x2; ··· xN ) which transforms as follows under a coordinate transformation: N i i X @x A = Aj(x1; x2; ··· xN ) @xj j=1 A covariant vector field is a set of N functions of xi 1 2 N Bi = Bi(x ; x ; ··· x ) which transforms as follows under a coordinate transformation: N X @xj B = B (x1; x2; ··· xN ) i @xi j j=1 i The scalar product of A and Bi is N X i A Bi i=1 which is invariant. Contravariant and covariant vectors form dual linear spaces. Length (squared) is defined as the scalar product of a vector with itself N 2 X i L = A Ai i=1 4 B2: Symmetry and Relativity J Tseng 1.3.1 Summation convention 1. Sum over an index which appears as both an \upper" (contravariant) and \lower" (covariant) index, from 1 to N. 2. A differential with respect to a contravariant coordinate (@=@xi) counts as a covariant index, and vice versa. N i i i X @x i @x A = Aj ) A = Aj @xj @xj j=1 N X i i A Bi ) A Bi i=1 When we begin to work explicitly with Minkowski space for Special Relativity, we will use different index types as a shorthand for their range: 1. Latin indices will range from 1 to 3, encompassing the spatial dimensions. 2. Greek indices will range from 0 to 3, with 0 corresponding to the time dimension. 1.3.2 Coordinate transformation matrices The coordinate transformation is often written in terms of a matrix @xi Λi = j @xj i i j A = Λ jA −1 j Ai = Aj(Λ ) i (The order of the last equation is simply to write it more obviously as a matrix multiplica- tion.) 1.4 Tensors A rank-2 tensor is a set of N 2 functions with the following transformation rules: • contravariant tensor i j ij @x @x C = Cab @xa @xb • covariant tensor @xa @xb C = C ij @xi @xj ab 5 B2: Symmetry and Relativity J Tseng • mixed tensor i b i @x @x C = Ca j @xa @xj b Higher rank tensors generalize these transformations. Vectors are rank-1 tensors. Tensors are said to be of the same kind when they have the same number and order (and type) of indices. 1.4.1 Tensor algebra Tensors of the same kind form a linear space. The outer product of two tensors of rank s and r is another tensor of rank s + r: i k i k T jS = C j A tensor of rank s can be contracted by summing over a pair of upper/lower indices, producing a tensor of rank s − 2: i A ji = Dj Quotient rule: if the inner product of N p functions A (with appropriate upper and lower indices) with an arbitrary tensor B is another tensor C then A is a rank-p tensor. 1.4.2 Special tensors i i A symmetric tensor is one where two indices can be swapped, e.g., A jk = A kj if A is symmetric in the jk indices. A skew-symmetric tensor, sometimes called an anti-symmetric tensor, flips sign when the i i specified indices are swapped, e.g., A jk = −A kj. i The Kronecker delta δj is a rank-2 mixed tensor. It is also isotropic in that it doesn't change under coordinate transformations. The related Kronecker delta δij is isotropic under linear transformations in a Euclidean space, but is not a tensor in general. 1.4.3 The metric The metric or fundamental tensor gij defines the line element 2 i j ds = gijdx dx It is also isotropic under linear transformations. ij jk k jk k The reciprocal fundamental tensor is g such that gijg = δi . (In general, AijA 6= δi .) A Cartesian coordinate system is one in which the components gij of the metric tensor are constants. 6 B2: Symmetry and Relativity J Tseng A Euclidean space is a space for which there exists a coordinate transformation to a system 2 i j where ds = δijdx dx . Index manipulation The fundamental tensor allows one to raise and lower indices. abjc ab c gijT d = T i d ij ab c abic g T j d = T d One can also flip the upper/lower indices in a contraction: i i T i = Ti 1.4.4 Levi-Civita tensor The Levi-Civita symbol eijk is defined to be skew-symmetric in all pairs of its indices, with e123 = +1. It is not a tensor in general. p The Levi-Civita tensor is defined to be ijk = jgjeijk, where jgj is the determinant of the metric, considered as a matrix. For Cartesian coordinate systems in Euclidean space, jgj = 1. 1.4.5 Caveats The following caveats apply to more general coordinate systems and transformations: 1. In non-Cartesian coordinate systems, the components gij are in general not equal to the components gij. 2. Even though the gradient of a scalar function @φ/∂xi (which we can write more suc- j cinctly as @iφ) transforms as a covariant vector, the gradient of a vector @iA is not in general a tensor. However, in this course we are mostly concerned with a Cartesian coordinate system of a Minkowski space in which the metric is known 0 −1 1 B 1 C gµν = B C @ 1 A 1 and we limit ourselves to linear transformations. In this case, the components of gµν are ν identical to gµν, and @µA transforms as a rank-2 mixed tensor. 7 B2: Symmetry and Relativity J Tseng 1.5 3D Physics tensors Examples of 3D tensors in physics. Note that since these reside in Euclidean space, con- travariant and covariant components transform in the same way, so the upper and lower indices here are used here mostly to imply summation. 1.5.1 Angular momentum Angular momentum can be written as a skew-symmetric outer product of position and momentum. Lij = xipj − xjpi The angular momentum vector is related to the tensor: jk Li = ijkL : In matrix form, 0 1 0 Lz −Ly ij L = @ −Lz 0 Lx A Ly −Lx 0 1.5.2 Moment of inertia Moment of inertia for a rigid body: Z ij 3 k ij i j I = d xρ(x)[(x xk)δ − x x ] V Angular momentum: i ij L = I !j where !j is the angular velocity vector. 1.5.3 Stress The stress tensor σij can be thought of as indicating the flow of the momentum component pi across face j of a volume. \Face j" refers to the face which is normal to the j direction. Stress tensor for an ideal fluid: 0 p 1 ij σ = @ p A p Euler equation for incompressible fluids: @ui 1 + uj@ ui = @ σij @t j ρ j where ui(xj) is the velocity of each point in the fluid. 8.
Load more

Recommended publications
  • Tensors and Differential Forms on Vector Spaces
    APPENDIX A TENSORS AND DIFFERENTIAL FORMS ON VECTOR SPACES Since only so much of the vast and growing field of differential forms and differentiable manifolds will be actually used in this survey, we shall attempt to briefly review how the calculus of exterior differential forms on vector spaces can serve as a replacement for the more conventional vector calculus and then introduce only the most elementary notions regarding more topologically general differentiable manifolds, which will mostly be used as the basis for the discussion of Lie groups, in the following appendix. Since exterior differential forms are special kinds of tensor fields – namely, completely-antisymmetric covariant ones – and tensors are important to physics, in their own right, we shall first review the basic notions concerning tensors and multilinear algebra. Presumably, the reader is familiar with linear algebra as it is usually taught to physicists, but for the “basis-free” approach to linear and multilinear algebra (which we shall not always adhere to fanatically), it would also help to have some familiarity with the more “abstract-algebraic” approach to linear algebra, such as one might learn from Hoffman and Kunze [ 1], for instance. 1. Tensor algebra. – A tensor algebra is a type of algebra in which multiplication takes the form of the tensor product. a. Tensor product. – Although the tensor product of vector spaces can be given a rigorous definition in a more abstract-algebraic context (See Greub [ 2], for instance), for the purposes of actual calculations with tensors and tensor fields, it is usually sufficient to say that if V and W are vector spaces of dimensions n and m, respectively, then the tensor product V ⊗ W will be a vector space of dimension nm whose elements are finite linear combinations of elements of the form v ⊗ w, where v is a vector in V and w is a vector in W.
    [Show full text]
  • Tensors Notation • Contravariant Denoted by Superscript Ai Took a Vector and Gave for Vector Calculus Us a Vector
    Tensors Notation • contravariant denoted by superscript Ai took a vector and gave For vector calculus us a vector • covariant denoted by subscript Ai took a scaler and gave us a vector Review To avoid confusion in cartesian coordinates both types are the same so • Vectors we just opt for the subscript. Thus a vector x would be x1,x2,x3 R3 • Summation representation of an n by n array As it turns out in an cartesian space and other rectilinear coordi- nate systems there is no difference between contravariant and covariant • Gradient, Divergence and Curl vectors. This will not be the case for other coordinate systems such a • Spherical Harmonics (maybe) curvilinear coordinate systems or in 4 dimensions. These definitions are closely related to the Jacobian. Motivation If you tape a book shut and try to spin it in the air on each indepen- Definitions for Tensors of Rank 2 dent axis you will notice that it spins fine on two axes but not on the Rank 2 tensors can be written as a square array. They have con- third. That’s the inertia tensor in your hands. Similar are the polar- travariant, mixed, and covariant forms. As we might expect in cartesian izations tensor, index of refraction tensor and stress tensor. But tensors coordinates these are the same. also show up in all sorts of places that don’t connect to an anisotropic material property, in fact even spherical harmonics are tensors. What are the similarities and differences between such a plethora of tensors? Vector Calculus and Identifers The mathematics of tensors is particularly useful for de- Tensor analysis extends deep into coordinate transformations of all scribing properties of substances which vary in direction– kinds of spaces and coordinate systems.
    [Show full text]
  • Multilinear Algebra
    Appendix A Multilinear Algebra This chapter presents concepts from multilinear algebra based on the basic properties of finite dimensional vector spaces and linear maps. The primary aim of the chapter is to give a concise introduction to alternating tensors which are necessary to define differential forms on manifolds. Many of the stated definitions and propositions can be found in Lee [1], Chaps. 11, 12 and 14. Some definitions and propositions are complemented by short and simple examples. First, in Sect. A.1 dual and bidual vector spaces are discussed. Subsequently, in Sects. A.2–A.4, tensors and alternating tensors together with operations such as the tensor and wedge product are introduced. Lastly, in Sect. A.5, the concepts which are necessary to introduce the wedge product are summarized in eight steps. A.1 The Dual Space Let V be a real vector space of finite dimension dim V = n.Let(e1,...,en) be a basis of V . Then every v ∈ V can be uniquely represented as a linear combination i v = v ei , (A.1) where summation convention over repeated indices is applied. The coefficients vi ∈ R arereferredtoascomponents of the vector v. Throughout the whole chapter, only finite dimensional real vector spaces, typically denoted by V , are treated. When not stated differently, summation convention is applied. Definition A.1 (Dual Space)Thedual space of V is the set of real-valued linear functionals ∗ V := {ω : V → R : ω linear} . (A.2) The elements of the dual space V ∗ are called linear forms on V . © Springer International Publishing Switzerland 2015 123 S.R.
    [Show full text]
  • Tensor Calculus and Differential Geometry
    Course Notes Tensor Calculus and Differential Geometry 2WAH0 Luc Florack March 10, 2021 Cover illustration: papyrus fragment from Euclid’s Elements of Geometry, Book II [8]. Contents Preface iii Notation 1 1 Prerequisites from Linear Algebra 3 2 Tensor Calculus 7 2.1 Vector Spaces and Bases . .7 2.2 Dual Vector Spaces and Dual Bases . .8 2.3 The Kronecker Tensor . 10 2.4 Inner Products . 11 2.5 Reciprocal Bases . 14 2.6 Bases, Dual Bases, Reciprocal Bases: Mutual Relations . 16 2.7 Examples of Vectors and Covectors . 17 2.8 Tensors . 18 2.8.1 Tensors in all Generality . 18 2.8.2 Tensors Subject to Symmetries . 22 2.8.3 Symmetry and Antisymmetry Preserving Product Operators . 24 2.8.4 Vector Spaces with an Oriented Volume . 31 2.8.5 Tensors on an Inner Product Space . 34 2.8.6 Tensor Transformations . 36 2.8.6.1 “Absolute Tensors” . 37 CONTENTS i 2.8.6.2 “Relative Tensors” . 38 2.8.6.3 “Pseudo Tensors” . 41 2.8.7 Contractions . 43 2.9 The Hodge Star Operator . 43 3 Differential Geometry 47 3.1 Euclidean Space: Cartesian and Curvilinear Coordinates . 47 3.2 Differentiable Manifolds . 48 3.3 Tangent Vectors . 49 3.4 Tangent and Cotangent Bundle . 50 3.5 Exterior Derivative . 51 3.6 Affine Connection . 52 3.7 Lie Derivative . 55 3.8 Torsion . 55 3.9 Levi-Civita Connection . 56 3.10 Geodesics . 57 3.11 Curvature . 58 3.12 Push-Forward and Pull-Back . 59 3.13 Examples . 60 3.13.1 Polar Coordinates in the Euclidean Plane .
    [Show full text]
  • C:\Book\Booktex\Notind.Dvi 0
    362 INDEX A Cauchy stress law 216 Absolute differentiation 120 Cauchy-Riemann equations 293,321 Absolute scalar field 43 Charge density 323 Absolute tensor 45,46,47,48 Christoffel symbols 108,110,111 Acceleration 121, 190, 192 Circulation 293 Action integral 198 Codazzi equations 139 Addition of systems 6, 51 Coefficient of viscosity 285 Addition of tensors 6, 51 Cofactors 25, 26, 32 Adherence boundary condition 294 Compatibility equations 259, 260, 262 Aelotropic material 245 Completely skew symmetric system 31 Affine transformation 86, 107 Compound pendulum 195,209 Airy stress function 264 Compressible material 231 Almansi strain tensor 229 Conic sections 151 Alternating tensor 6,7 Conical coordinates 74 Ampere’s law 176,301,337,341 Conjugate dyad 49 Angle between vectors 80, 82 Conjugate metric tensor 36, 77 Angular momentum 218, 287 Conservation of angular momentum 218, 295 Angular velocity 86,87,201,203 Conservation of energy 295 Arc length 60, 67, 133 Conservation of linear momentum 217, 295 Associated tensors 79 Conservation of mass 233, 295 Auxiliary Magnetic field 338 Conservative system 191, 298 Axis of symmetry 247 Conservative electric field 323 B Constitutive equations 242, 251,281, 287 Continuity equation 106,234, 287, 335 Basic equations elasticity 236, 253, 270 Contraction 6, 52 Basic equations for a continuum 236 Contravariant components 36, 44 Basic equations of fluids 281, 287 Contravariant tensor 45 Basis vectors 1,2,37,48 Coordinate curves 37, 67 Beltrami 262 Coordinate surfaces 37, 67 Bernoulli’s Theorem 292 Coordinate transformations
    [Show full text]
  • A Mathematica Package for Doing Tensor Calculations in Differential Geometry User's Manual
    Ricci A Mathematica package for doing tensor calculations in differential geometry User’s Manual Version 1.32 By John M. Lee assisted by Dale Lear, John Roth, Jay Coskey, and Lee Nave 2 Ricci A Mathematica package for doing tensor calculations in differential geometry User’s Manual Version 1.32 By John M. Lee assisted by Dale Lear, John Roth, Jay Coskey, and Lee Nave Copyright c 1992–1998 John M. Lee All rights reserved Development of this software was supported in part by NSF grants DMS-9101832, DMS-9404107 Mathematica is a registered trademark of Wolfram Research, Inc. This software package and its accompanying documentation are provided as is, without guarantee of support or maintenance. The copyright holder makes no express or implied warranty of any kind with respect to this software, including implied warranties of merchantability or fitness for a particular purpose, and is not liable for any damages resulting in any way from its use. Everyone is granted permission to copy, modify and redistribute this software package and its accompanying documentation, provided that: 1. All copies contain this notice in the main program file and in the supporting documentation. 2. All modified copies carry a prominent notice stating who made the last modifi- cation and the date of such modification. 3. No charge is made for this software or works derived from it, with the exception of a distribution fee to cover the cost of materials and/or transmission. John M. Lee Department of Mathematics Box 354350 University of Washington Seattle, WA 98195-4350 E-mail: [email protected] Web: http://www.math.washington.edu/~lee/ CONTENTS 3 Contents 1 Introduction 6 1.1Overview..............................
    [Show full text]
  • Appendix a Relations Between Covariant and Contravariant Bases
    Appendix A Relations Between Covariant and Contravariant Bases The contravariant basis vector gk of the curvilinear coordinate of uk at the point P is perpendicular to the covariant bases gi and gj, as shown in Fig. A.1.This contravariant basis gk can be defined as or or a gk g  g ¼  ðA:1Þ i j oui ou j where a is the scalar factor; gk is the contravariant basis of the curvilinear coordinate of uk. Multiplying Eq. (A.1) by the covariant basis gk, the scalar factor a results in k k ðgi  gjÞ: gk ¼ aðg : gkÞ¼ad ¼ a ÂÃk ðA:2Þ ) a ¼ðgi  gjÞ : gk gi; gj; gk The scalar triple product of the covariant bases can be written as pffiffiffi a ¼ ½¼ðg1; g2; g3 g1  g2Þ : g3 ¼ g ¼ J ðA:3Þ where Jacobian J is the determinant of the covariant basis tensor G. The direction of the cross product vector in Eq. (A.1) is opposite if the dummy indices are interchanged with each other in Einstein summation convention. Therefore, the Levi-Civita permutation symbols (pseudo-tensor components) can be used in expression of the contravariant basis. ffiffiffi p k k g g ¼ J g ¼ðgi  gjÞ¼Àðgj  giÞ eijkðgi  gjÞ eijkðgi  gjÞ ðA:4Þ ) gk ¼ pffiffiffi ¼ g J where the Levi-Civita permutation symbols are defined by 8 <> þ1ifði; j; kÞ is an even permutation; eijk ¼ > À1ifði; j; kÞ is an odd permutation; : A:5 0ifi ¼ j; or i ¼ k; or j ¼ k ð Þ 1 , e ¼ ði À jÞÁðj À kÞÁðk À iÞ for i; j; k ¼ 1; 2; 3 ijk 2 H.
    [Show full text]
  • Mechanics of Continuous Media in $(\Bar {L} N, G) $-Spaces. I
    Mechanics of Continuous Media in (Ln, g)-spaces. I. Introduction and mathematical tools S. Manoff Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy, Department of Theoretical Physics, Blvd. Tzarigradsko Chaussee 72 1784 Sofia - Bulgaria e-mail address: [email protected] Abstract Basic notions and mathematical tools in continuum media mechanics are recalled. The notion of exponent of a covariant differential operator is intro- duced and on its basis the geometrical interpretation of the curvature and the torsion in (Ln,g)-spaces is considered. The Hodge (star) operator is general- ized for (Ln,g)-spaces. The kinematic characteristics of a flow are outline in brief. PACS numbers: 11.10.-z; 11.10.Ef; 7.10.+g; 47.75.+f; 47.90.+a; 83.10.Bb 1 Introduction 1.1 Differential geometry and space-time geometry arXiv:gr-qc/0203016v1 5 Mar 2002 In the last years, the evolution of the relations between differential geometry and space-time geometry has made some important steps toward applications of more comprehensive differential-geometric structures in the models of space-time than these used in (pseudo) Riemannian spaces without torsion (Vn-spaces) [1], [2]. 1. Recently, it has been proved that every differentiable manifold with one affine connection and metrics [(Ln,g)-space] [3], [4] could be used as a model for a space- time. In it, the equivalence principle (related to the vanishing of the components of an affine connection at a point or on a curve in a manifold) holds [5] ÷ [11], [12]. Even if the manifold has two different (not only by sign) connections for tangent and co-tangent vector fields [(Ln,g)-space] [13], [14] the principle of equivalence is fulfilled at least for one of the two types of vector fields [15].
    [Show full text]
  • Arxiv:1412.2393V4 [Gr-Qc] 27 Feb 2019 2.6 Geodesics and Normal Coordinates
    Riemannian Geometry: Definitions, Pictures, and Results Adam Marsh February 27, 2019 Abstract A pedagogical but concise overview of Riemannian geometry is provided, in the context of usage in physics. The emphasis is on defining and visualizing concepts and relationships between them, as well as listing common confusions, alternative notations and jargon, and relevant facts and theorems. Special attention is given to detailed figures and geometric viewpoints, some of which would seem to be novel to the literature. Topics are avoided which are well covered in textbooks, such as historical motivations, proofs and derivations, and tools for practical calculations. As much material as possible is developed for manifolds with connection (omitting a metric) to make clear which aspects can be readily generalized to gauge theories. The presentation in most cases does not assume a coordinate frame or zero torsion, and the coordinate-free, tensor, and Cartan formalisms are developed in parallel. Contents 1 Introduction 2 2 Parallel transport 3 2.1 The parallel transporter . 3 2.2 The covariant derivative . 4 2.3 The connection . 5 2.4 The covariant derivative in terms of the connection . 6 2.5 The parallel transporter in terms of the connection . 9 arXiv:1412.2393v4 [gr-qc] 27 Feb 2019 2.6 Geodesics and normal coordinates . 9 2.7 Summary . 10 3 Manifolds with connection 11 3.1 The covariant derivative on the tensor algebra . 12 3.2 The exterior covariant derivative of vector-valued forms . 13 3.3 The exterior covariant derivative of algebra-valued forms . 15 3.4 Torsion . 16 3.5 Curvature .
    [Show full text]
  • Differential Geometric Algebra with Leibniz and Grassmann Michael Reed (Crucial Flow Research)
    Proceedings of JuliaCon Differential geometric algebra with Leibniz and Grassmann Michael Reed (Crucial Flow Research) The nature of the geometric algebra code generation enables one to easily extend the abstract product operations to any specific number field type (including differential operators with Leibniz.jl or symbolic coefficients with Reduce.jl), by making use of Julia’s type system. Mixed tensor products with their coefficients are constructed from these operations to work with bivector elements of Lie groups [7][10]. 1. Direct sum parametric type polymorphism The DirectSum.jl package is a work in progress providing the necessary tools to work with an arbitrary Manifold specified github.com/chakravala/Grassmann.jl by an encoding. Due to the parametric type system for the generating VectorBundle, the Julia compiler can fully pre- allocate and often cache values efficiently ahead of run-time. Although intended for use with the Grassmann.jl package, ABSTRACT DirectSum can be used independently. The Grassmann.jl package provides tools for computations based on multi-linear algebra and spin groups using the Definition 1 Vector bundle of submanifolds. Let 푀 = 푇 휇푉 ∈ TensorBundle<:Manifold 푛 extended geometric algebra known as Leibniz-Grassmann- Vect핂 be a of rank , Clifford-Hestenes algebra. Combinatorial products include 휇 푇 푉 = (푛, ℙ, 푔, 휈, 휇), ℙ ⊆ ⟨푣∞, 푣∅⟩ , 푔 ∶ 푉 × 푉 → 핂 exterior, regressive, inner, and geometric; along with the Hodge star, adjoint, reversal, and boundary operators. The The type TensorBundle{n,ℙ,g,휈, 휇} uses byte-encoded data kernelized operations are built up from composite sparse available at pre-compilation, where ℙ specifies the basis for tensor products and Hodge duality, with high dimensional up and down projection, 푔 is a bilinear form that specifies the support for up to 62 indices using staged caching and pre- metric of the space, and 휇 is an integer specifying the order of compilation.
    [Show full text]
  • Induced Representations of Tensors and Spinors of Any Rank in the SHP Theory
    Induced Representations of Tensors and Spinors of any Rank in the SHP Theory Lawrence P. Horwitz Raymond and Beverly Sackler Faculty of Exact Science, School of Physic, Tel Aviv University, Ramat Aviv 69978, Israel. Physics Department, Bar Ilan University, Ramat Gan 52900, Israel. Israel Physics Department, Ariel University, Ariel 40700, Israel Email: [email protected] Meir Zeilig-Hess Raymond and Beverly Sackler Faculty of Exact Science, School of Physic, Tel Aviv University, Ramat Aviv 69978, Israel. Email: [email protected] Abstract We show that a modification of Wigner's induced representation for the description of a relativistic particle with spin can be used to construct spinors and tensors of arbitrary rank, with invariant decomposition over angular momentum. In particular, scalar and vector fields, as well as the representations of their transformations, are constructed. The method that is developed here admits the construction of wave packets and states of a many body relativistic system with definite total angular momentum. Furthermore, a Pauli-Lubanski operator is constructed on the orbit of the induced representation which provides a Casimir operator for the Poincaré group and which contains the physical intrinsic angular momentum of the particle covariantly. 1 Introduction 1.1 Foundations of the SHP theory The theory of Stueckelberg-Horwitz-Piron (called SHP henceforth) was initiated by Stueckelberg's suggestion, according to which pairs of particles can be created and/or annihilated throughout the motion of a single particle, in a way which can be described by classical equations of motions in space-time[1]. The evolution parameter, , of such particle trajectories is an invariant under Lorentz transformations.
    [Show full text]
  • On Dynamic Equations for Interaction of the Affinor Field with Affine Connection
    SUffOWf объединенный ИНСТИТУТ ядерных исследований дубна Е2-8 7-826 A.B.Peetov ON DYNAMIC EQUATIONS FOR INTERACTION OF THE AFFINOR FIELD WITH AFFINE CONNECTION Submitted to XXI International Symposium on Elementary Particle Theory, GDR, 1987. 1987 INTRODUCTION Of fundamental importance for the theory of strong, elect­ romagnetic, and gravitational interactions are such tensor fields as a scalar field, covariant vector field, covariant skew-symmetric tensor field of the second rank, covariant sym­ metric tensor field of the second rank; this list of the sim­ plest tensor fields of rank not higher than the second is in­ complete since it does not contain a mixed tensor field of the second rank that is called the affinor field. If one re­ calls that general relativity is essentially the theory of a symmetric tensor field of the second rank, it is quite natu­ ral to assume that the theory of the affinor field is not on­ ly of a pure mathematical interest. In this report devoted to the theory of affinor field I consider a model of two interacting fields, one of which is an affinor field and the other is a non-tensor field called the affine connection. I. LAGRANGIAN OF THE AFFINOR FIELD Out of two affinors So and Тд an affinor may be construc­ ted called their product P0 = Sa T/3- (I) If Is/8 I Ф 0, there exists an affinor Sg inverse to 8я , S"S^1<7=S_10S^= 8j§. With the operation of multiplication thus defined, the set of affinors with a nonzero determinant forms a group, denoted by Gi , which plays a fundamental role in the theory of affinor field as the group of internal sym­ metry.
    [Show full text]