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super Poincare Lie algebra

Context

\infty-Lie theory

∞-Lie theory

Background

Smooth structure

Higher groupoids

Lie theory

∞-Lie groupoids

∞-Lie algebroids

Formal Lie groupoids

Cohomology

Homotopy

Examples

\infty-Lie groupoids

\infty-Lie groups

\infty-Lie algebroids

\infty-Lie algebras

Super-Geometry

Contents

Idea

The super Poincaré Lie algebra is a super Lie algebra extension of a Poincaré Lie algebra.

The corresponding super Lie group is the super Euclidean group (except for the signature of the metric).

Definition

Let dd \in \mathbb{N} and consider Minkowski spacetime d1,1\mathbb{R} ^{d-1,1} of dimension dd. For Spin(d1,1)Spin(d-1,1) the corresponding spin group, let

SRep(Spin(d1,1)) S \in Rep(Spin(d-1,1))

be a spin representation with the property that there exists a linear map

Γ:SS d1,1 \Gamma \;\colon\; S \otimes S \longrightarrow \mathbb{R}^{d-1,1}

which is

  1. symmetric:

  2. Spin(V)Spin(V) equivariant (a homomorphism of spin representations).

For a classification of spin representations with this property see at spin representations the sections real irreducible spin representations in Lorentz signature and super Poincaré brackets.

Definition

The super Poincaré Lie algebra 𝔰𝔦𝔰𝔬 S(d1,1)\mathfrak{siso}_S(d-1,1) of dd-dimensional Minkowski spacetime with respect to the spin representation SS with symmetric and Spin(V)Spin(V)-equivariant pairing Γ:SS d1,1\Gamma \colon S \otimes S \to \mathbb{R}^{d-1,1} is the super Lie algebra extension of the Poincaré Lie algebra by ΠS\Pi S (the vector space underlying SS taken in odd degree)

ΠS𝔰𝔦𝔰𝔬 S(d1,1)𝔦𝔰𝔬(d1,1) d1,1𝔰𝔬(d1,1), \Pi S \longrightarrow \mathfrak{siso}_S(d-1,1) \longrightarrow \mathfrak{iso}(d-1,1) \simeq \mathbb{R}^{d-1,1} \ltimes \mathfrak{so}(d-1,1) \,,

where the Lie bracket of elements in 𝔰𝔬(d1,1)\mathfrak{so}(d-1,1) with those in SS is the given action, the Lie bracket of elements of d1,1\mathbb{R}^{d-1,1} with those on SS is trivial, and the Lie bracket of two elements s 1,s 2Ss_1, s_2 \in S is given by Γ\Gamma:

[s 1,s 2]Γ(s 1,s 2). [s_1,s_2] \coloneqq \Gamma(s_1,s_2) \,.
Remark

It is precisely the symmetry and Spin(V)Spin(V)-equivariant assumption on Γ\Gamma that makes this a well defined super Lie algebra: the symmetry corresponds to the graded skew-symmetry of the Lie bracket on elements in SS, which are regarded as odd, and the Spin(V)Spin(V)-equivariance yields the nontrivial Jacobi identity for o𝔰𝔬(d1,1)o \in \mathfrak{so}(d-1,1) and s 1,s 2Ss_1, s_2 \in S:

Γ([o,s 1],s 2)+Γ(s 1,[o,s 2])=[o,Γ(s 1,s 2)]. \Gamma([o,s_1], s_2) + \Gamma(s_1, [o,s_2]) = [o, \Gamma(s_1,s_2)] \,.
Remark

By the general discussion at Chevalley-Eilenberg algebra, we may characterize the super Poincaré Lie algebra 𝔰𝔦𝔰𝔬 S(D1,1)\mathfrak{siso}_S(D-1,1) by its CE super-dg-algebra CE(𝔰𝔦𝔰𝔬 S(D1,1))CE(\mathfrak{siso}_S(D-1,1)) “of left-invariant 1-forms” on its group manifold.

Write {ω a b} a,b\{\omega_a{}^b\}_{a,b} for the canonical basis of the special orthogonal matrix Lie algebra 𝔰𝔬(D1,1)\mathfrak{so}(D-1,1) and write {ψ α} α\{\psi_\alpha\}_\alpha for a corresponding basis of the spin representation SS.

The Chevalley-Eilenberg algebra CE(𝔰𝔦𝔰𝔬 N(d1,1))CE(\mathfrak{siso}_N(d-1,1)) is generated on

  • elements {e a}\{e^a\} and {ω ab}\{\omega^{ a b}\} of degree (1,even)(1,even)

  • and elements {ψ α}\{\psi^\alpha\} of degree (1,odd)(1,odd)

with the differential defined by

d CEω ab=ω a bω bc d_{CE} \omega^{a b} = \omega^a{}_b \wedge \omega^{b c}
d CEe a=ω a be b+i2ψ¯Γ aψ d_{CE} e^{a } = \omega^a{}_b \wedge e^b + \frac{i}{2}\bar \psi \Gamma^a \psi
d CEψ=14ω abΓ abψ. d_{CE} \psi = \frac{1}{4} \omega^{ a b} \wedge \Gamma_{a b} \psi \,.
Remark

Removing all terms involving ω\omega here yields the Chevalley-Eilenberg algebra of the super translation algebra D;N\mathbb{R}^{D;N}.

Remark

The abstract generators in def. 2 are identified with left invariant 1-forms on the super-translation group as follows.

Let (x a,θ α)(x^a, \theta^\alpha) be the canonical coordinates on the supermanifold d|N\mathbb{R}^{d|N} underlying the super translation group. Then the identification is

  • ψ α=dθ α\psi^\alpha = d \theta^\alpha.

  • e a=dx a+i2θ¯Γ adθe^a = d x^a + \frac{i}{2} \overline{\theta} \Gamma^a d \theta.

This then gives the formula for the differential of the super-vielbein in def. 2 as

de a =d(dx a+i2θ¯Γ adθ) =i2dθ¯Γ adθ =i2ψ¯Γ aψ. \begin{aligned} d e^a & = d (d x^a + \frac{i}{2} \overline{\theta} \Gamma^a d \theta) \\ & = \frac{i}{2} d \overline{\theta}\Gamma^a d \theta \\ & = \frac{i}{2} \overline{\psi}\Gamma^a \psi \end{aligned} \,.

Properties

Lie algebra cohomology

The super Poincaré Lie algebra has, on top of the Lie algebra cocycles that it inherits from 𝔰𝔬(n)\mathfrak{so}(n), a discrete number of exceptiona cocycles bilinear in the spinors, on the super translation algebra, that exist only in very special dimensions.

The following theorem has been stated at various placed in the physics literature (known there as the brane scan for κ\kappa-symmetry in Green-Schwarz action functionals for super-pp-branes on super-Minkowski spacetime). A full proof is in Brandt 12-13. The following uses the notation in terms of division algebras (Baez-Huerta 10).

Theorem

  • In dimensional d=3,4,6,10d = 3,4,6, 10, 𝔰𝔦𝔰𝔬(d1,1)\mathfrak{siso}(d-1,1) has a nontrivial 3-cocycle given by

    (ψ,ϕ,A)g(ψϕ,A) (\psi, \phi, A) \mapsto g(\psi \cdot \phi, A)

    for spinors ψ,ϕ𝒮\psi, \phi \in \mathcal{S} and vectors A𝒯A \in \mathcal{T}, and 0 otherwise.

  • In dimensional d=4,5,7,11d = 4,5,7, 11, 𝔰𝔦𝔰𝔬(d1,1)\mathfrak{siso}(d-1,1) has a nontrivial 4-cocycle given by

    (Ψ,Φ,𝒜,)Ψ,(𝒜𝒜)Φ (\Psi, \Phi, \mathcal{A}, \mathcal{B}) \mapsto \langle \Psi , (\mathcal{A}\mathcal{B}- \mathcal{B} \mathcal{A})\Phi \rangle

    for spinors Ψ,Φ𝒮\Psi, \Phi \in \mathcal{S} and vectors 𝒜,𝒱\mathcal{A}, \mathcal{B} \in \mathcal{V}, with the commutator taken in the Clifford algebra.

The 4-cocycle in d=11d = 11 is the one that induces the supergravity Lie 3-algebra.

All these cocycles are controled by the relevant Fierz identities.

Extensions

Super L L_\infty-algebra extensions

The super L-infinity algebra infinity-Lie algebra cohomology of the super Poincaré Lie algebra corresponding to the above cocycles involves

supergravity Lie 6-algebra \to supergravity Lie 3-algebra \to super-Poincaré Lie algebra

Extended super Poincaré Lie algebra – Polyvector extensions

The super-Poincaré Lie algebra has a class of super Lie algebra extensions called extended supersymmetry algebras or polyvector extensions , because they involve additional generators that transforn as skew-symmetric tensors. A complete classification is in (ACDP).

For instance the “M-theory Lie algebra” is a polyvector extension of the super Poincaré Lie algebra 𝔰𝔦𝔰𝔬 N=1(10,1)\mathfrak{siso}_{N=1}(10,1) by polyvectors of rank p=2p = 2 and p=5p=5 (the M2-brane and the M5-brane in the brane scan), see below Polyvector extensions as automorphism Lie algebras.

As automorphism Lie algebras of Lie nn-superalgebras

At least some of the polyvector extensions of the super Poincaré Lie algebra arise as the automorphism super Lie algebras of the Lie n-algebra extensions classified by the cocycles discussed above.

For instance the automorphisms of the supergravity Lie 3-algebra gives the “M-theory Lie algebra”-extension of super-Poincaré in 11-dimensions (FSS 13). This is also discussed at supergravity Lie 3-algebra – Polyvector extensions.

References

General

The seminal classification result of simple supersymmetry algebras is due to

  • Werner Nahm, Supersymmetries and their Representations, Nucl.Phys. B135 (1978) 149 (spire)

Lecture notes include

See also

for discussion in the view of the brane scan and The brane bouquet of super-pp-brane Green-Schwarz sigma-models.

Polyvector extensions

A comprehensive account and classification of the polyvector extensions of the super Poincaré Lie algebras is in

Super Lie algebra cohomology

The super-Lie algebra cohomology of the super Poincare Lie algebra is discussed in

and completely classified in

  • Friedemann Brandt, Supersymmetry algebra cohomology

    I: Definition and general structure J. Math. Phys.51:122302, 2010, (arXiv:0911.2118)

    II: Primitive elements in 2 and 3 dimensions, J. Math. Phys. 51 (2010) 112303 (arXiv:1004.2978)

    III: Primitive elements in four and five dimensions, J. Math. Phys. 52:052301, 2011 (arXiv:1005.2102)

    IV: Primitive elements in all dimensions from D=4D=4 to D=11D=11, J. Math. Phys. 54, 052302 (2013) (arXiv:1303.6211)

A classification of some special cases of signature/supersymmetry of this is also in the following (using a computer algebra system):

For applications of this classification see also at Green-Schwarz action functional and at brane scan.

An introduction to the exceptional fermionic cocycles on the super Poincaré Lie algebra, and their description using normed division algebras, are discussed here:

This subsumes some of the results in (Azcárraga-Townend)

Discussion of the corresponding super L-∞ algebra L-∞ extensions in the context of Green-Schwarz action functionals and ∞-Wess-Zumino-Witten theory is in

A direct constructions of ordinary (Lie algebraic) extensions of the super Poincare Lie algebra by means of division algebras is in

  • Jerzy Lukierski, Francesco Toppan, Generalized Space-time Supersymmetries, Division Algebras and Octonionic M-theory (pdf)

For more on this see at division algebra and supersymmetry.

Revised on October 9, 2013 11:37:30 by Urs Schreiber (89.204.139.155)