Representation theory of Lie groups | Rotation in three dimensions

Representation theory of SU(2)

In the study of the representation theory of Lie groups, the study of representations of SU(2) is fundamental to the study of representations of semisimple Lie groups. It is the first case of a Lie group that is both a compact group and a non-abelian group. The first condition implies the representation theory is discrete: representations are direct sums of a collection of basic irreducible representations (governed by the Peter–Weyl theorem). The second means that there will be irreducible representations in dimensions greater than 1. SU(2) is the universal covering group of SO(3), and so its representation theory includes that of the latter, by dint of a surjective homomorphism to it. This underlies the significance of SU(2) for the description of non-relativistic spin in theoretical physics; see for other physical and historical context. As shown below, the finite-dimensional irreducible representations of SU(2) are indexed by a non-negative integer and have dimension . In the physics literature, the representations are labeled by the quantity , where is then either an integer or a half-integer, and the dimension is . (Wikipedia).

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Representation theory: Introduction

This lecture is an introduction to representation theory of finite groups. We define linear and permutation representations, and give some examples for the icosahedral group. We then discuss the problem of writing a representation as a sum of smaller ones, which leads to the concept of irr

From playlist Representation theory

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RT6. Representations on Function Spaces

Representation Theory: We note how to transfer a group action of a group G on a set X to a group action on F(X), the functions on X. Because F(X) is a vector space, we obtain a representation of the group, and we can apply previous techniques. In particular, the group acts on itself in

From playlist Representation Theory

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Representation Theory as Gauge Theory - David Ben-Zvi [2016]

Slides for this talk: https://drive.google.com/file/d/1FHl_tIOjp26vuULi0gkSgoIN7PMnKLXK/view?usp=sharing Notes for this talk: https://drive.google.com/file/d/1BpP2Sz_zHWa_SQLM6DC6T8b4v_VKZs1A/view?usp=sharing David Ben-Zvi (University of Texas, Austin) Title: Representation Theory as G

From playlist Number Theory

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Representation theory: Induced representations

We define induced representations of finite groups in two ways as either left or right adjoints of the restriction functor. We calculate the character of an induced representation, and give an example of an induced representation of S3.

From playlist Representation theory

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RT1: Representation Theory Basics

Representation Theory: We present basic concepts about the representation theory of finite groups. Representations are defined, as are notions of invariant subspace, irreducibility and full reducibility. For a general finite group G, we suggest an analogue to the finite abelian case, whe

From playlist *** The Good Stuff ***

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RT2: Unitary Representations

Representation Theory: We explain unitarity and invariant inner products for representations of finite groups. Full reducibility of such representations is derived. Course materials, including problem sets and solutions, available at http://mathdoctorbob.org/UR-RepTheory.html

From playlist Representation Theory

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Representation theory: Abelian groups

This lecture discusses the complex representations of finite abelian groups. We show that any group is iomorphic to its dual (the group of 1-dimensional representations, and isomorphic to its double dual in a canonical way (Pontryagin duality). We check the orthogonality relations for the

From playlist Representation theory

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PiTP-Supersymmetric Grand Unification, Part 1 - Stuart Raby

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From playlist PiTP 2008

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Representation theory: Orthogonality relations

This lecture is about the orthogonality relations of the character table of complex representations of a finite group. We show that these representations are unitary and deduce that they are all sums of irreducible representations. We then prove Schur's lemma describing the dimension of t

From playlist Representation theory

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SQCD and Pairs of Pants by Shlomo Razamat

PROGRAM QUANTUM FIELDS, GEOMETRY AND REPRESENTATION THEORY 2021 (ONLINE) ORGANIZERS: Aswin Balasubramanian (Rutgers University, USA), Indranil Biswas (TIFR, india), Jacques Distler (The University of Texas at Austin, USA), Chris Elliott (University of Massachusetts, USA) and Pranav Pan

From playlist Quantum Fields, Geometry and Representation Theory 2021 (ONLINE)

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A Mathematical Introduction to 3d N = 4 Gauge Theories (Lecture 1) by Mathew Bullimore

PROGRAM : QUANTUM FIELDS, GEOMETRY AND REPRESENTATION THEORY 2021 (ONLINE) ORGANIZERS : Aswin Balasubramanian (Rutgers University, USA), Indranil Biswas (TIFR, india), Jacques Distler (The University of Texas at Austin, USA), Chris Elliott (University of Massachusetts, USA) and Pranav Pan

From playlist Quantum Fields, Geometry and Representation Theory 2021 (ONLINE)

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PiTP-Supersymmetric Grand Unification, Part 2 - Stuart Raby

PiTP-Supersymmetric Grand Unification, Part 2 Stuart Raby The Ohio State University July 17, 2008

From playlist PiTP 2008

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An Introduction to Class-S and Tinkertoys (Lecture 2 )by Jacques Distler

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From playlist Quantum Fields, Geometry and Representation Theory

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Lecture 4 | New Revolutions in Particle Physics: Standard Model

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From playlist Lecture Collection | Particle Physics: Standard Model

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Supersymmetric gauge theories (Lecture 4) by Shiraz Minwalla

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From playlist Kavli Asian Winter School (KAWS) on Strings, Particles and Cosmology 2018

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Workshop 1 "Operator Algebras and Quantum Information Theory" - CEB T3 2017 - M.Brannan

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From playlist 2017 - T3 - Analysis in Quantum Information Theory - CEB Trimester

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A simple Qubit Regularization Scheme for SU(N) Lattice Gauge Theories by Shailesh Chandrasekharan

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From playlist NUMSTRING 2022

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RT4.2. Schur's Lemma (Expanded)

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From playlist Representation Theory

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Wall Crossing, Part 1 - Greg Moore

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From playlist PiTP 2010

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Weyl character formula | Commutator | Pauli matrices | Special unitary group | Unit vector | Representation theory of semisimple Lie algebras | Maximal torus | Lorentz group | Representation of a Lie group | Quaternion | Borel–Weil–Bott theorem | Three-dimensional space | Peter–Weyl theorem | Adjoint representation | Spin (physics) | William Rowan Hamilton | Delta baryon | Non-abelian group | Baryon | Complexification | Representation theory | Rotation | Schur's lemma | Representation theory of SL2(R) | Real number | Group theory | Euclidean space | Mathematical induction | Versor | Compact group | Casimir element | Projective representation | Complex number | Character (mathematics) | Matrix multiplication | Universal enveloping algebra | Rotation operator (quantum mechanics) | Fundamental representation | Geometry | Matrix (mathematics) | Irreducible representation | Rotation (mathematics)