Automorphic Products on Unitary Groups
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Topological Modes in Dual Lattice Models
Topological Modes in Dual Lattice Models Mark Rakowski 1 Dublin Institute for Advanced Studies, 10 Burlington Road, Dublin 4, Ireland Abstract Lattice gauge theory with gauge group ZP is reconsidered in four dimensions on a simplicial complex K. One finds that the dual theory, formulated on the dual block complex Kˆ , contains topological modes 2 which are in correspondence with the cohomology group H (K,Zˆ P ), in addition to the usual dynamical link variables. This is a general phenomenon in all models with single plaquette based actions; the action of the dual theory becomes twisted with a field representing the above cohomology class. A similar observation is made about the dual version of the three dimensional Ising model. The importance of distinct topological sectors is confirmed numerically in the two di- 1 mensional Ising model where they are parameterized by H (K,Zˆ 2). arXiv:hep-th/9410137v1 19 Oct 1994 PACS numbers: 11.15.Ha, 05.50.+q October 1994 DIAS Preprint 94-32 1Email: [email protected] 1 Introduction The use of duality transformations in statistical systems has a long history, beginning with applications to the two dimensional Ising model [1]. Here one finds that the high and low temperature properties of the theory are related. This transformation has been extended to many other discrete models and is particularly useful when the symmetries involved are abelian; see [2] for an extensive review. All these studies have been confined to hypercubic lattices, or other regular structures, and these have rather limited global topological features. Since lattice models are defined in a way which depends clearly on the connectivity of links or other regions, one expects some sort of topological effects generally. -
Construction of Free Subgroups in the Group of Units of Modular Group Algebras
CONSTRUCTION OF FREE SUBGROUPS IN THE GROUP OF UNITS OF MODULAR GROUP ALGEBRAS Jairo Z. Gon¸calves1 Donald S. Passman2 Department of Mathematics Department of Mathematics University of S~ao Paulo University of Wisconsin-Madison 66.281-Ag Cidade de S. Paulo Van Vleck Hall 05389-970 S. Paulo 480 Lincoln Drive S~ao Paulo, Brazil Madison, WI 53706, U.S.A [email protected] [email protected] Abstract. Let KG be the group algebra of a p0-group G over a field K of characteristic p > 0; and let U(KG) be its group of units. If KG contains a nontrivial bicyclic unit and if K is not algebraic over its prime field, then we prove that the free product Zp ∗ Zp ∗ Zp can be embedded in U(KG): 1. Introduction Let KG be the group algebra of the group G over the field K; and let U(KG) be its group of units. Motivated by the work of Pickel and Hartley [4], and Sehgal ([7, pg. 200]) on the existence of free subgroups in the inte- gral group ring ZG; analogous conditions for U(KG) have been intensively investigated in [1], [2] and [3]. Recently Marciniak and Sehgal [5] gave a constructive method for produc- ing free subgroups in U(ZG); provided ZG contains a nontrivial bicyclic unit. In this paper we prove an analogous result for the modular group algebra KG; whenever K is not algebraic over its prime field GF (p): Specifically, if Zp denotes the cyclic group of order p, then we prove: 1- Research partially supported by CNPq - Brazil. -
Special Unitary Group - Wikipedia
Special unitary group - Wikipedia https://en.wikipedia.org/wiki/Special_unitary_group Special unitary group In mathematics, the special unitary group of degree n, denoted SU( n), is the Lie group of n×n unitary matrices with determinant 1. (More general unitary matrices may have complex determinants with absolute value 1, rather than real 1 in the special case.) The group operation is matrix multiplication. The special unitary group is a subgroup of the unitary group U( n), consisting of all n×n unitary matrices. As a compact classical group, U( n) is the group that preserves the standard inner product on Cn.[nb 1] It is itself a subgroup of the general linear group, SU( n) ⊂ U( n) ⊂ GL( n, C). The SU( n) groups find wide application in the Standard Model of particle physics, especially SU(2) in the electroweak interaction and SU(3) in quantum chromodynamics.[1] The simplest case, SU(1) , is the trivial group, having only a single element. The group SU(2) is isomorphic to the group of quaternions of norm 1, and is thus diffeomorphic to the 3-sphere. Since unit quaternions can be used to represent rotations in 3-dimensional space (up to sign), there is a surjective homomorphism from SU(2) to the rotation group SO(3) whose kernel is {+ I, − I}. [nb 2] SU(2) is also identical to one of the symmetry groups of spinors, Spin(3), that enables a spinor presentation of rotations. Contents Properties Lie algebra Fundamental representation Adjoint representation The group SU(2) Diffeomorphism with S 3 Isomorphism with unit quaternions Lie Algebra The group SU(3) Topology Representation theory Lie algebra Lie algebra structure Generalized special unitary group Example Important subgroups See also 1 of 10 2/22/2018, 8:54 PM Special unitary group - Wikipedia https://en.wikipedia.org/wiki/Special_unitary_group Remarks Notes References Properties The special unitary group SU( n) is a real Lie group (though not a complex Lie group). -
The Mathematics of Lattices
The Mathematics of Lattices Daniele Micciancio January 2020 Daniele Micciancio (UCSD) The Mathematics of Lattices Jan 2020 1 / 43 Outline 1 Point Lattices and Lattice Parameters 2 Computational Problems Coding Theory 3 The Dual Lattice 4 Q-ary Lattices and Cryptography Daniele Micciancio (UCSD) The Mathematics of Lattices Jan 2020 2 / 43 Point Lattices and Lattice Parameters 1 Point Lattices and Lattice Parameters 2 Computational Problems Coding Theory 3 The Dual Lattice 4 Q-ary Lattices and Cryptography Daniele Micciancio (UCSD) The Mathematics of Lattices Jan 2020 3 / 43 Key to many algorithmic applications Cryptanalysis (e.g., breaking low-exponent RSA) Coding Theory (e.g., wireless communications) Optimization (e.g., Integer Programming with fixed number of variables) Cryptography (e.g., Cryptographic functions from worst-case complexity assumptions, Fully Homomorphic Encryption) Point Lattices and Lattice Parameters (Point) Lattices Traditional area of mathematics ◦ ◦ ◦ Lagrange Gauss Minkowski Daniele Micciancio (UCSD) The Mathematics of Lattices Jan 2020 4 / 43 Point Lattices and Lattice Parameters (Point) Lattices Traditional area of mathematics ◦ ◦ ◦ Lagrange Gauss Minkowski Key to many algorithmic applications Cryptanalysis (e.g., breaking low-exponent RSA) Coding Theory (e.g., wireless communications) Optimization (e.g., Integer Programming with fixed number of variables) Cryptography (e.g., Cryptographic functions from worst-case complexity assumptions, Fully Homomorphic Encryption) Daniele Micciancio (UCSD) The Mathematics of Lattices Jan 2020 4 / 43 Point Lattices and Lattice Parameters Lattice Cryptography: a Timeline 1982: LLL basis reduction algorithm Traditional use of lattice algorithms as a cryptanalytic tool 1996: Ajtai's connection Relates average-case and worst-case complexity of lattice problems Application to one-way functions and collision resistant hashing 2002: Average-case/worst-case connection for structured lattices. -
Chapter 1 GENERAL STRUCTURE and PROPERTIES
Chapter 1 GENERAL STRUCTURE AND PROPERTIES 1.1 Introduction In this Chapter we would like to introduce the main de¯nitions and describe the main properties of groups, providing examples to illustrate them. The detailed discussion of representations is however demanded to later Chapters, and so is the treatment of Lie groups based on their relation with Lie algebras. We would also like to introduce several explicit groups, or classes of groups, which are often encountered in Physics (and not only). On the one hand, these \applications" should motivate the more abstract study of the general properties of groups; on the other hand, the knowledge of the more important and common explicit instances of groups is essential for developing an e®ective understanding of the subject beyond the purely formal level. 1.2 Some basic de¯nitions In this Section we give some essential de¯nitions, illustrating them with simple examples. 1.2.1 De¯nition of a group A group G is a set equipped with a binary operation , the group product, such that1 ¢ (i) the group product is associative, namely a; b; c G ; a (b c) = (a b) c ; (1.2.1) 8 2 ¢ ¢ ¢ ¢ (ii) there is in G an identity element e: e G such that a e = e a = a a G ; (1.2.2) 9 2 ¢ ¢ 8 2 (iii) each element a admits an inverse, which is usually denoted as a¡1: a G a¡1 G such that a a¡1 = a¡1 a = e : (1.2.3) 8 2 9 2 ¢ ¢ 1 Notice that the axioms (ii) and (iii) above are in fact redundant. -
Electromagnetic Duality for Children
Electromagnetic Duality for Children JM Figueroa-O'Farrill [email protected] Version of 8 October 1998 Contents I The Simplest Example: SO(3) 11 1 Classical Electromagnetic Duality 12 1.1 The Dirac Monopole ....................... 12 1.1.1 And in the beginning there was Maxwell... 12 1.1.2 The Dirac quantisation condition . 14 1.1.3 Dyons and the Zwanziger{Schwinger quantisation con- dition ........................... 16 1.2 The 't Hooft{Polyakov Monopole . 18 1.2.1 The bosonic part of the Georgi{Glashow model . 18 1.2.2 Finite-energy solutions: the 't Hooft{Polyakov Ansatz . 20 1.2.3 The topological origin of the magnetic charge . 24 1.3 BPS-monopoles .......................... 26 1.3.1 Estimating the mass of a monopole: the Bogomol'nyi bound ........................... 27 1.3.2 Saturating the bound: the BPS-monopole . 28 1.4 Duality conjectures ........................ 30 1.4.1 The Montonen{Olive conjecture . 30 1.4.2 The Witten e®ect ..................... 31 1.4.3 SL(2; Z) duality ...................... 33 2 Supersymmetry 39 2.1 The super-Poincar¶ealgebra in four dimensions . 40 2.1.1 Some notational remarks about spinors . 40 2.1.2 The Coleman{Mandula and Haag{ÃLopusza¶nski{Sohnius theorems .......................... 42 2.2 Unitary representations of the supersymmetry algebra . 44 2.2.1 Wigner's method and the little group . 44 2.2.2 Massless representations . 45 2.2.3 Massive representations . 47 No central charges .................... 48 Adding central charges . 49 1 [email protected] draft version of 8/10/1998 2.3 N=2 Supersymmetric Yang-Mills . -
The Enumerative Geometry of Rational and Elliptic Tropical Curves and a Riemann-Roch Theorem in Tropical Geometry
The enumerative geometry of rational and elliptic tropical curves and a Riemann-Roch theorem in tropical geometry Michael Kerber Am Fachbereich Mathematik der Technischen Universit¨atKaiserslautern zur Verleihung des akademischen Grades Doktor der Naturwissenschaften (Doctor rerum naturalium, Dr. rer. nat.) vorgelegte Dissertation 1. Gutachter: Prof. Dr. Andreas Gathmann 2. Gutachter: Prof. Dr. Ilia Itenberg Abstract: The work is devoted to the study of tropical curves with emphasis on their enumerative geometry. Major results include a conceptual proof of the fact that the number of rational tropical plane curves interpolating an appropriate number of general points is independent of the choice of points, the computation of intersection products of Psi- classes on the moduli space of rational tropical curves, a computation of the number of tropical elliptic plane curves of given genus and fixed tropical j-invariant as well as a tropical analogue of the Riemann-Roch theorem for algebraic curves. Mathematics Subject Classification (MSC 2000): 14N35 Gromov-Witten invariants, quantum cohomology 51M20 Polyhedra and polytopes; regular figures, division of spaces 14N10 Enumerative problems (combinatorial problems) Keywords: Tropical geometry, tropical curves, enumerative geometry, metric graphs. dedicated to my parents — in love and gratitude Contents Preface iii Tropical geometry . iii Complex enumerative geometry and tropical curves . iv Results . v Chapter Synopsis . vi Publication of the results . vii Financial support . vii Acknowledgements . vii 1 Moduli spaces of rational tropical curves and maps 1 1.1 Tropical fans . 2 1.2 The space of rational curves . 9 1.3 Intersection products of tropical Psi-classes . 16 1.4 Moduli spaces of rational tropical maps . -
Hilbert Geometry of the Siegel Disk: the Siegel-Klein Disk Model
Hilbert geometry of the Siegel disk: The Siegel-Klein disk model Frank Nielsen Sony Computer Science Laboratories Inc, Tokyo, Japan Abstract We study the Hilbert geometry induced by the Siegel disk domain, an open bounded convex set of complex square matrices of operator norm strictly less than one. This Hilbert geometry yields a generalization of the Klein disk model of hyperbolic geometry, henceforth called the Siegel-Klein disk model to differentiate it with the classical Siegel upper plane and disk domains. In the Siegel-Klein disk, geodesics are by construction always unique and Euclidean straight, allowing one to design efficient geometric algorithms and data-structures from computational geometry. For example, we show how to approximate the smallest enclosing ball of a set of complex square matrices in the Siegel disk domains: We compare two generalizations of the iterative core-set algorithm of Badoiu and Clarkson (BC) in the Siegel-Poincar´edisk and in the Siegel-Klein disk: We demonstrate that geometric computing in the Siegel-Klein disk allows one (i) to bypass the time-costly recentering operations to the disk origin required at each iteration of the BC algorithm in the Siegel-Poincar´edisk model, and (ii) to approximate fast and numerically the Siegel-Klein distance with guaranteed lower and upper bounds derived from nested Hilbert geometries. Keywords: Hyperbolic geometry; symmetric positive-definite matrix manifold; symplectic group; Siegel upper space domain; Siegel disk domain; Hilbert geometry; Bruhat-Tits space; smallest enclosing ball. 1 Introduction German mathematician Carl Ludwig Siegel [106] (1896-1981) and Chinese mathematician Loo-Keng Hua [52] (1910-1985) have introduced independently the symplectic geometry in the 1940's (with a preliminary work of Siegel [105] released in German in 1939). -
Lattice Basics II Lattice Duality. Suppose First That
Math 272y: Rational Lattices and their Theta Functions 11 September 2019: Lattice basics II Lattice duality. Suppose first that V is a finite-dimensional real vector space without any further structure, and let V ∗ be its dual vector space, V ∗ = Hom(V; R). We may still define a lattice L ⊂ V as a discrete co-compact subgroup, or concretely (but not canonically) as the Z-span of an R-basis e1; : : : ; en. The dual lattice is then L∗ := fx∗ 2 V ∗ : 8y 2 L; x∗(y) 2 Zg: 1 This is indeed a lattice: we readily see that if e1; : : : ; en is a Z-basis for L then the dual basis ∗ ∗ ∗ ∗ e1; : : : ; en is a Z-basis for L . It soon follows that L = Hom(L; Z) (that is, every homomorphism L ! Z is realized by a unique x∗ 2 L∗), and — as suggested by the “dual” terminology — the ∗ ∗ ∗ ∗ canonical identification of the double dual (V ) with V takes the dual basis of e1; : : : ; en back to ∗ e1; : : : ; en, and thus takes the dual of L back to L. Once we have chosen some basis for V, and thus an identification V =∼ Rn, we can write any basis as the columns of some invertible matrix M, and then that basis generates the lattice MZn; the dual basis then consists of the row vectors of −1 n −1 ∗ ∗ M , so the dual lattice is Z M (in coordinates that make e1; : : : ; en unit vectors). We shall soon use Fourier analysis on V and on its quotient torus V=L. In this context, V ∗ is the Pontrjagin dual of V : any x∗ 2 V ∗ gives a continuous homomorphism y 7! exp(2πi x∗(y)) from V to the unit circle. -
MODULAR GROUP IMAGES ARISING from DRINFELD DOUBLES of DIHEDRAL GROUPS Deepak Naidu 1. Introduction the Modular Group SL(2, Z) Is
International Electronic Journal of Algebra Volume 28 (2020) 156-174 DOI: 10.24330/ieja.768210 MODULAR GROUP IMAGES ARISING FROM DRINFELD DOUBLES OF DIHEDRAL GROUPS Deepak Naidu Received: 28 October 2019; Revised: 30 May 2020; Accepted: 31 May 2020 Communicated by A. C¸i˘gdem Ozcan¨ Abstract. We show that the image of the representation of the modular group SL(2; Z) arising from the representation category Rep(D(G)) of the Drinfeld double D(G) is isomorphic to the group PSL(2; Z=nZ) × S3, when G is either the dihedral group of order 2n or the dihedral group of order 4n for some odd integer n ≥ 3. Mathematics Subject Classification (2020): 18M20 Keywords: Drinfeld double, modular tensor category, modular group, con- gruence subgroup 1. Introduction The modular group SL(2; Z) is the group of all 2 × 2 matrices of determinant 1 whose entries belong to the ring Z of integers. The modular group is known to play a significant role in conformal field theory [3]. Every two-dimensional rational con- formal field theory gives rise to a finite-dimensional representation of the modular group, and the kernel of this representation has been of much interest. In particu- lar, the question whether the kernel is a congruence subgroup of SL(2; Z) has been investigated by several authors. For example, A. Coste and T. Gannon in their paper [4] showed that under certain assumptions the kernel is indeed a congruence subgroup. In the present paper, we consider the kernel of the representation of the modular group arising from Drinfeld doubles of dihedral groups. -
The Modular Group Action on Real SL(2)–Characters of a One-Holed Torus
ISSN 1364-0380 (on line) 1465-3060 (printed) 443 Geometry & Topology G T T G G T T Volume 7 (2003) 443–486 G T G T T G T Published: 18 July 2003 G T G T G Republished with corrections: 21 August 2003 T G T G G T G G G T T The modular group action on real SL(2)–characters of a one-holed torus William M Goldman Mathematics Department, University of Maryland College Park, MD 20742 USA Email: [email protected] Abstract The group Γ of automorphisms of the polynomial κ(x,y,z)= x2 + y2 + z2 − xyz − 2 is isomorphic to PGL(2, Z) ⋉ (Z/2 ⊕ Z/2). For t ∈ R, the Γ-action on κ−1(t) ∩ R3 displays rich and varied dynamics. The action of Γ preserves a Poisson structure defining a Γ–invariant area form on each κ−1(t) ∩ R3 . For t < 2, the action of Γ is properly discontinuous on the four con- tractible components of κ−1(t) ∩ R3 and ergodic on the compact component (which is empty if t < −2). The contractible components correspond to Teichm¨uller spaces of (possibly singular) hyperbolic structures on a torus M¯ . For t = 2, the level set κ−1(t) ∩ R3 consists of characters of reducible representations and comprises two er- godic components corresponding to actions of GL(2, Z) on (R/Z)2 and R2 respectively. For 2 <t ≤ 18, the action of Γ on κ−1(t) ∩ R3 is ergodic. Corresponding to the Fricke space of a three-holed sphere is a Γ–invariant open subset Ω ⊂ R3 whose components are permuted freely by a subgroup of index 6 in Γ. -
Classification of Special Reductive Groups 11
CLASSIFICATION OF SPECIAL REDUCTIVE GROUPS ALEXANDER MERKURJEV Abstract. We give a classification of special reductive groups over arbitrary fields that improves a theorem of M. Huruguen. 1. Introduction An algebraic group G over a field F is called special if for every field extension K=F all G-torsors over K are trivial. Examples of special linear groups include: 1. The general linear group GLn, and more generally the group GL1(A) of invertible elements in a central simple F -algebra A; 2. The special linear group SLn and the symplectic group Sp2n; 3. Quasi-trivial tori, and more generally invertible tori (direct factors of quasi-trivial tori). 4. If L=F is a finite separable field extension and G is a special group over L, then the Weil restriction RL=F (G) is a special group over F . A. Grothendieck proved in [3] that a reductive group G over an algebraically closed field is special if and only if the derived subgroup of G is isomorphic to the product of special linear groups and symplectic groups. In [4] M. Huruguen proved the following theorem. Theorem. Let G be a reductive group over a field F . Then G is special if and only if the following three condition hold: (1) The derived subgroup G0 of G is isomorphic to RL=F (SL1(A)) × RK=F (Sp(h)) where L and K are ´etale F -algebras, A an Azumaya algebra over L and h an alternating non-degenerate form over K. (2) The coradical G=G0 of G is an invertible torus.