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Lie theory · Group

SU(2)\mathrm{SU}(2)Special unitary group

The simply connected compact group with Lie algebra su(2). Its irreducible complex representations are indexed by spin j = 0, ½, 1, … .

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Executable coverageSpinGauge theory
Definition

2 × 2 complex unitary matrices of determinant 1

Definition sources
Real dimension
33
Source and assumptions
Center
Z2\mathbb Z_{2}
Source and assumptions
Fundamental group
00
Source and assumptions

Reference properties

PropertyValueEvidence
Real dimension33Sources
CenterZ2\mathbb Z_{2}Sources
Fundamental group00Sources
CompactYesSources
ConnectedYesSources
Rank11Sources

Representations

Highest weight n = 2j ≥ 0; dimension n + 1. Even n has real type, odd n quaternionic type. [sources]

Topology and global form

SU(2) is diffeomorphic to S³. The central quotient by {±I} is SO(3). [sources]

In physics

Angular momentum, spin, weak isospin, and the basic example of a spin cover. [sources]

Names and aliases

Spin(3) · Sp(1)

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Claims and sources

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Definition

2 × 2 complex unitary matrices of determinant 1

group:su-2#definition
Real dimension

3

group:su-2#dimension
Center

ℤ₂

group:su-2#center
Fundamental group

0

group:su-2#pi1
Compact

Yes

group:su-2#compact
Connected

Yes

group:su-2#connected
Rank

1

group:su-2#rank
Representations

Highest weight n = 2j ≥ 0; dimension n + 1. Even n has real type, odd n quaternionic type.

group:su-2#representations-1
Topology and global form

SU(2) is diffeomorphic to S³. The central quotient by {±I} is SO(3).

group:su-2#topology-1
In physics

Angular momentum, spin, weak isospin, and the basic example of a spin cover.

group:su-2#physics-1
Related group

group:so-3

group:su-2#relation-1
Related group

group:q-8

group:su-2#relation-2
Related group

group:su-3

group:su-2#relation-3
Actual real Lie algebra

algebra:su-2-r

group:su-2#relation-4
Real-form context

real-form:su-2-r

group:su-2#relation-5
Explicit homomorphism

map:su-2-to-so-3

group:su-2#relation-6
Explicit homomorphism

map:su-2-to-su-3-regular

group:su-2#relation-7
Explicit homomorphism

map:su-2-to-su-3-principal

group:su-2#relation-8
Explicit homomorphism

map:u-1-to-su-2

group:su-2#relation-9
Specified homogeneous quotient

space:su-2-over-u-1

group:su-2#relation-10