Representation of Lie Algebra with Application to Particles Physics
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Nilpotent Lie Groups and Hyperbolic Automorphisms ”
Nilpotent Lie groups and hyperbolic automorphisms Manoj Choudhuri and C. R. E. Raja Abstract A connected Lie group admitting an expansive automorphism is known to be nilotent, but all nilpotent Lie groups do not admit expansive au- tomorphism. In this article, we find sufficient conditions for a class of nilpotent Lie groups to admit expansive automorphism. Let G be a locally compact (second countable) group and Aut(G) be the group of (continuous) automorphisms of G. We consider automorphisms α of G that have a specific property that there is a neighborhood U of identity such that n ∩n∈Zα (U) = {e} - such automorphisms are known as expansive. The struc- ture of compact connected groups admitting expansive automorphism has been studied in [6], [7], [17], [10] and it was shown in [10] that a compact connected group admitting an expansive automorphism is abelian. The same problen has been studied for totally disconnected groups as well, see [9] and [16] for com- pact totally disconnected groups and a recent paper of Helge Glockner and the second named author ([8]) for locally compact totally disconnected groups. In [14], Riddhi Shah has shown that a connected locally compact group admitting expansive automorphism is nilpotent. The result was known previously for Lie groups (see Proposition 7.1 of [8] or Proposition 2.2 of [14] for a proof of this fact and further references). But all nilpotent Lie groups do not admit expansive automorphism which can be seen easily by considering the circle group. In this article, we try to classify a class of nilpotent Lie groups which admit expansive automorphism. -
Note on the Decomposition of Semisimple Lie Algebras
Note on the Decomposition of Semisimple Lie Algebras Thomas B. Mieling (Dated: January 5, 2018) Presupposing two criteria by Cartan, it is shown that every semisimple Lie algebra of finite dimension over C is a direct sum of simple Lie algebras. Definition 1 (Simple Lie Algebra). A Lie algebra g is Proposition 2. Let g be a finite dimensional semisimple called simple if g is not abelian and if g itself and f0g are Lie algebra over C and a ⊆ g an ideal. Then g = a ⊕ a? the only ideals in g. where the orthogonal complement is defined with respect to the Killing form K. Furthermore, the restriction of Definition 2 (Semisimple Lie Algebra). A Lie algebra g the Killing form to either a or a? is non-degenerate. is called semisimple if the only abelian ideal in g is f0g. Proof. a? is an ideal since for x 2 a?; y 2 a and z 2 g Definition 3 (Derived Series). Let g be a Lie Algebra. it holds that K([x; z; ]; y) = K(x; [z; y]) = 0 since a is an The derived series is the sequence of subalgebras defined ideal. Thus [a; g] ⊆ a. recursively by D0g := g and Dn+1g := [Dng;Dng]. Since both a and a? are ideals, so is their intersection Definition 4 (Solvable Lie Algebra). A Lie algebra g i = a \ a?. We show that i = f0g. Let x; yi. Then is called solvable if its derived series terminates in the clearly K(x; y) = 0 for x 2 i and y = D1i, so i is solv- trivial subalgebra, i.e. -
Lecture 5: Semisimple Lie Algebras Over C
LECTURE 5: SEMISIMPLE LIE ALGEBRAS OVER C IVAN LOSEV Introduction In this lecture I will explain the classification of finite dimensional semisimple Lie alge- bras over C. Semisimple Lie algebras are defined similarly to semisimple finite dimensional associative algebras but are far more interesting and rich. The classification reduces to that of simple Lie algebras (i.e., Lie algebras with non-zero bracket and no proper ideals). The classification (initially due to Cartan and Killing) is basically in three steps. 1) Using the structure theory of simple Lie algebras, produce a combinatorial datum, the root system. 2) Study root systems combinatorially arriving at equivalent data (Cartan matrix/ Dynkin diagram). 3) Given a Cartan matrix, produce a simple Lie algebra by generators and relations. In this lecture, we will cover the first two steps. The third step will be carried in Lecture 6. 1. Semisimple Lie algebras Our base field is C (we could use an arbitrary algebraically closed field of characteristic 0). 1.1. Criteria for semisimplicity. We are going to define the notion of a semisimple Lie algebra and give some criteria for semisimplicity. This turns out to be very similar to the case of semisimple associative algebras (although the proofs are much harder). Let g be a finite dimensional Lie algebra. Definition 1.1. We say that g is simple, if g has no proper ideals and dim g > 1 (so we exclude the one-dimensional abelian Lie algebra). We say that g is semisimple if it is the direct sum of simple algebras. Any semisimple algebra g is the Lie algebra of an algebraic group, we can take the au- tomorphism group Aut(g). -
Irreducible Representations of Complex Semisimple Lie Algebras
Irreducible Representations of Complex Semisimple Lie Algebras Rush Brown September 8, 2016 Abstract In this paper we give the background and proof of a useful theorem classifying irreducible representations of semisimple algebras by their highest weight, as well as restricting what that highest weight can be. Contents 1 Introduction 1 2 Lie Algebras 2 3 Solvable and Semisimple Lie Algebras 3 4 Preservation of the Jordan Form 5 5 The Killing Form 6 6 Cartan Subalgebras 7 7 Representations of sl2 10 8 Roots and Weights 11 9 Representations of Semisimple Lie Algebras 14 1 Introduction In this paper I build up to a useful theorem characterizing the irreducible representations of semisim- ple Lie algebras, namely that finite-dimensional irreducible representations are defined up to iso- morphism by their highest weight ! and that !(Hα) is an integer for any root α of R. This is the main theorem Fulton and Harris use for showing that the Weyl construction for sln gives all (finite-dimensional) irreducible representations. 1 In the first half of the paper we'll see some of the general theory of semisimple Lie algebras| building up to the existence of Cartan subalgebras|for which we will use a mix of Fulton and Harris and Serre ([1] and [2]), with minor changes where I thought the proofs needed less or more clarification (especially in the proof of the existence of Cartan subalgebras). Most of them are, however, copied nearly verbatim from the source. In the second half of the paper we will describe the roots of a semisimple Lie algebra with respect to some Cartan subalgebra, the weights of irreducible representations, and finally prove the promised result. -
Algebraic D-Modules and Representation Theory Of
Contemporary Mathematics Volume 154, 1993 Algebraic -modules and Representation TheoryDof Semisimple Lie Groups Dragan Miliˇci´c Abstract. This expository paper represents an introduction to some aspects of the current research in representation theory of semisimple Lie groups. In particular, we discuss the theory of “localization” of modules over the envelop- ing algebra of a semisimple Lie algebra due to Alexander Beilinson and Joseph Bernstein [1], [2], and the work of Henryk Hecht, Wilfried Schmid, Joseph A. Wolf and the author on the localization of Harish-Chandra modules [7], [8], [13], [17], [18]. These results can be viewed as a vast generalization of the classical theorem of Armand Borel and Andr´e Weil on geometric realiza- tion of irreducible finite-dimensional representations of compact semisimple Lie groups [3]. 1. Introduction Let G0 be a connected semisimple Lie group with finite center. Fix a maximal compact subgroup K0 of G0. Let g be the complexified Lie algebra of G0 and k its subalgebra which is the complexified Lie algebra of K0. Denote by σ the corresponding Cartan involution, i.e., σ is the involution of g such that k is the set of its fixed points. Let K be the complexification of K0. The group K has a natural structure of a complex reductive algebraic group. Let π be an admissible representation of G0 of finite length. Then, the submod- ule V of all K0-finite vectors in this representation is a finitely generated module over the enveloping algebra (g) of g, and also a direct sum of finite-dimensional U irreducible representations of K0. -
LIE GROUPS and ALGEBRAS NOTES Contents 1. Definitions 2
LIE GROUPS AND ALGEBRAS NOTES STANISLAV ATANASOV Contents 1. Definitions 2 1.1. Root systems, Weyl groups and Weyl chambers3 1.2. Cartan matrices and Dynkin diagrams4 1.3. Weights 5 1.4. Lie group and Lie algebra correspondence5 2. Basic results about Lie algebras7 2.1. General 7 2.2. Root system 7 2.3. Classification of semisimple Lie algebras8 3. Highest weight modules9 3.1. Universal enveloping algebra9 3.2. Weights and maximal vectors9 4. Compact Lie groups 10 4.1. Peter-Weyl theorem 10 4.2. Maximal tori 11 4.3. Symmetric spaces 11 4.4. Compact Lie algebras 12 4.5. Weyl's theorem 12 5. Semisimple Lie groups 13 5.1. Semisimple Lie algebras 13 5.2. Parabolic subalgebras. 14 5.3. Semisimple Lie groups 14 6. Reductive Lie groups 16 6.1. Reductive Lie algebras 16 6.2. Definition of reductive Lie group 16 6.3. Decompositions 18 6.4. The structure of M = ZK (a0) 18 6.5. Parabolic Subgroups 19 7. Functional analysis on Lie groups 21 7.1. Decomposition of the Haar measure 21 7.2. Reductive groups and parabolic subgroups 21 7.3. Weyl integration formula 22 8. Linear algebraic groups and their representation theory 23 8.1. Linear algebraic groups 23 8.2. Reductive and semisimple groups 24 8.3. Parabolic and Borel subgroups 25 8.4. Decompositions 27 Date: October, 2018. These notes compile results from multiple sources, mostly [1,2]. All mistakes are mine. 1 2 STANISLAV ATANASOV 1. Definitions Let g be a Lie algebra over algebraically closed field F of characteristic 0. -
Introuduction to Representation Theory of Lie Algebras
Introduction to Representation Theory of Lie Algebras Tom Gannon May 2020 These are the notes for the summer 2020 mini course on the representation theory of Lie algebras. We'll first define Lie groups, and then discuss why the study of representations of simply connected Lie groups reduces to studying representations of their Lie algebras (obtained as the tangent spaces of the groups at the identity). We'll then discuss a very important class of Lie algebras, called semisimple Lie algebras, and we'll examine the repre- sentation theory of two of the most basic Lie algebras: sl2 and sl3. Using these examples, we will develop the vocabulary needed to classify representations of all semisimple Lie algebras! Please email me any typos you find in these notes! Thanks to Arun Debray, Joakim Færgeman, and Aaron Mazel-Gee for doing this. Also{thanks to Saad Slaoui and Max Riestenberg for agreeing to be teaching assistants for this course and for many, many helpful edits. Contents 1 From Lie Groups to Lie Algebras 2 1.1 Lie Groups and Their Representations . .2 1.2 Exercises . .4 1.3 Bonus Exercises . .4 2 Examples and Semisimple Lie Algebras 5 2.1 The Bracket Structure on Lie Algebras . .5 2.2 Ideals and Simplicity of Lie Algebras . .6 2.3 Exercises . .7 2.4 Bonus Exercises . .7 3 Representation Theory of sl2 8 3.1 Diagonalizability . .8 3.2 Classification of the Irreducible Representations of sl2 .............8 3.3 Bonus Exercises . 10 4 Representation Theory of sl3 11 4.1 The Generalization of Eigenvalues . -
Arxiv:1208.0416V2 [Math.RT] 6 Sep 2012 Itoutr)Gaut Ore Ntesubject
REPRESENTATIONS OF COMPLEX SEMI-SIMPLE LIE GROUPS AND LIE ALGEBRAS APOORVA KHARE† Abstract. This article is an exposition of the 1967 paper by Parthasarathy, Ranga Rao, and Varadarajan, on irreducible admissible Harish-Chandra modules over complex semisimple Lie groups and Lie algebras. It was written in Winter 2012 to be part of a special collection organized to mark 10 years and 25 volumes of the series Texts and Readings in Mathematics (TRIM). Each article in this collection is intended to give nonspecialists in its field, an appreciation for the impact and contributions of the paper being surveyed. Thus, the author has kept the prerequisites for this article down to a basic course on complex semisimple Lie algebras. While it arose out of the grand program of Harish-Chandra on admissible representations of semisimple Lie groups, the work by Parthasarathy et al also provided several new insights on highest weight modules and related areas, and these results have been the subject of extensive research over the last four decades. Thus, we also discuss its results and follow-up works on the classification of irreducible Harish-Chandra modules; on the PRV conjecture and tensor product multiplicities; and on PRV determinants for (quantized) affine and semisimple Lie algebras. Contents 1. Notation and preliminaries 3 2. Harish-Chandra modules 5 3. Tensor products, minimal types, and the (K)PRV conjecture 10 4. IrreducibleBanachspacerepresentations 15 5. The rings Rν,Π′ and the PRV determinants 21 6. Representations of class zero 26 7. Conclusion: The classification of irreducible Harish-Chandra modules 27 References 29 arXiv:1208.0416v2 [math.RT] 6 Sep 2012 Lie groups and Lie algebras occupy a prominent and central place in mathematics, connecting differential geometry, representation theory, algebraic geometry, number theory, and theoretical physics. -
Representation Theory
M392C NOTES: REPRESENTATION THEORY ARUN DEBRAY MAY 14, 2017 These notes were taken in UT Austin's M392C (Representation Theory) class in Spring 2017, taught by Sam Gunningham. I live-TEXed them using vim, so there may be typos; please send questions, comments, complaints, and corrections to [email protected]. Thanks to Kartik Chitturi, Adrian Clough, Tom Gannon, Nathan Guermond, Sam Gunningham, Jay Hathaway, and Surya Raghavendran for correcting a few errors. Contents 1. Lie groups and smooth actions: 1/18/172 2. Representation theory of compact groups: 1/20/174 3. Operations on representations: 1/23/176 4. Complete reducibility: 1/25/178 5. Some examples: 1/27/17 10 6. Matrix coefficients and characters: 1/30/17 12 7. The Peter-Weyl theorem: 2/1/17 13 8. Character tables: 2/3/17 15 9. The character theory of SU(2): 2/6/17 17 10. Representation theory of Lie groups: 2/8/17 19 11. Lie algebras: 2/10/17 20 12. The adjoint representations: 2/13/17 22 13. Representations of Lie algebras: 2/15/17 24 14. The representation theory of sl2(C): 2/17/17 25 15. Solvable and nilpotent Lie algebras: 2/20/17 27 16. Semisimple Lie algebras: 2/22/17 29 17. Invariant bilinear forms on Lie algebras: 2/24/17 31 18. Classical Lie groups and Lie algebras: 2/27/17 32 19. Roots and root spaces: 3/1/17 34 20. Properties of roots: 3/3/17 36 21. Root systems: 3/6/17 37 22. Dynkin diagrams: 3/8/17 39 23. -
The Fourier Transform for Nilpotent Locally Compact Groups. I
Pacific Journal of Mathematics THE FOURIER TRANSFORM FOR NILPOTENT LOCALLY COMPACT GROUPS. I ROGER EVANS HOWE Vol. 73, No. 2 April 1977 PACIFIC JOURNAL OF MATHEMATICS Vol. 73, No. 2, 1977 THE FOURIER TRANSFORM FOR NILPOTENT LOCALLY COMPACT GROUPS: I ROGER E. HOWE In his work on nilpotent lie groups, A. A. Kirillov intro- duced the idea of classifying the representations of such groups by matching them with orbits in the dual of the lie algebra under the coadjoint action. His methods have proved extremely fruitful, and subsequent authors have refined and extended them to the point where they provide highly satisfac- tory explanations of many aspects of the harmonic analysis of various lie groups. Meanwhile, it appears that nonlie groups are also amenable to such an approach. In this paper, we seek to indicate that, indeed, a very large class of separable, locally compact, nilpotent groups have a Kirillov- type theory. On the other hand, elementary examples show that not all such groups can have a perfect Kirillov theory. The precise boundary between good and bad groups is not well defined, and varies with the amount of technical complication you can tolerate. At this stage, the delineation of the boundary is the less rewarding part of the theory, and will be deferred to a future publication. In the present paper, we lay some groundwork, and then discuss a particularly nice special case, which also has significance in the general picture. Since Kirillov's approach hinges on the use of the lie algebra and its dual, the first concern in imitating his theory is to find a lie algebra. -
Canonical Coordinates on Lie Groups and the Baker Campbell Hausdorff Formula
Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 8-2018 Canonical Coordinates on Lie Groups and the Baker Campbell Hausdorff Formula Nicholas Graner Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Mathematics Commons Recommended Citation Graner, Nicholas, "Canonical Coordinates on Lie Groups and the Baker Campbell Hausdorff Formula" (2018). All Graduate Theses and Dissertations. 7232. https://digitalcommons.usu.edu/etd/7232 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. CANONICAL COORDINATES ON LIE GROUPS AND THE BAKER CAMPBELL HAUSDORFF FORMULA by Nicholas Graner A thesis submitted in partial fulfillment of the requirements for the degree of MASTERS OF SCIENCE in Mathematics Approved: Mark Fels, Ph.D. Charles Torre, Ph.D. Major Professor Committee Member Ian Anderson, Ph.D. Mark R. McLellan, Ph.D. Committee Member Vice President for Research and Dean of the School for Graduate Studies UTAH STATE UNIVERSITY Logan,Utah 2018 ii Copyright © Nicholas Graner 2018 All Rights Reserved iii ABSTRACT Canonical Coordinates on Lie Groups and the Baker Campbell Hausdorff Formula by Nicholas Graner, Master of Science Utah State University, 2018 Major Professor: Mark Fels Department: Mathematics and Statistics Lie's third theorem states that for any finite dimensional Lie algebra g over the real numbers, there is a simply connected Lie group G which has g as its Lie algebra. -
An Introduction to Lie Algebras and the Theorem of Ado
An introduction to Lie algebras and the theorem of Ado Hofer Joachim 28.01.2012 An introduction to Lie algebras and the theorem of Ado Contents Introduction 2 1 Lie algebras 3 1.1 Subalgebras, ideals, quotients . 4 1.2 Nilpotent, solvable, simple and semisimple Lie algebras . 5 2 The representation theory of Lie algebras 7 2.1 Examples . 7 2.2 Modules, submodules, quotient modules . 7 2.3 Structure theorems: Lie and Engel . 8 3 The theorem of Ado for nilpotent Lie algebras. How can a faithful representation be constructed? 11 3.1 Ad hoc examples . 11 3.2 The universal enveloping algebra . 11 3.2.1 Tensor products and the tensor algebra . 11 3.2.2 The universal enveloping algebra of a Lie algebra . 12 3.2.3 The Poincare-Birkhoff-Witt theorem . 12 3.3 Constructing a faithful representation of h1 ............................... 12 3.4 Ado’s theorem for nilpotent Lie algebras . 13 3.5 Constructing a faithful representation for the standard filiform Lie algebra of dimension 4 . 14 3.6 Constructing a faithful representation for an abelian Lie algebra . 15 4 The theorem of Ado 16 4.1 Derivations . 16 4.2 Direct and semidirect sums of Lie algebras . 16 4.3 Proof of Ado’s theorem . 17 4.4 Proof of Neretin’s lemma . 18 4.5 Constructing a faithful representation of the 2-dimensional upper triangular matrices . 19 4.6 Constructing a faithful representation of an abstract Lie algebra . 19 1 Hofer Joachim An introduction to Lie algebras and the theorem of Ado Introduction Lie groups and Lie algebras are of great importance in modern physics, particularly in the context of (continu- ous) symmetry transformations.