Supersymmetry algebras in 1 + 1 dimensions

A two dimensional Minkowski space, i.e. a flat space with one time and one spatial dimension, has a two-dimensional Poincaré group IO(1,1) as its symmetry group. The respective Lie algebra is called the Poincaré algebra. It is possible to extend this algebra to a supersymmetry algebra, which is a \mathbb{Z}_2-graded Lie superalgebra. The most common ways to do this are discussed below.

{{nowrap|''N''{{=}}(2,2)}} algebra

Let the Lie algebra of IO(1,1) be generated by the following generators:

  • H = P_0

is the generator of the time translation,

  • P = P_1

is the generator of the space translation,

For the commutators between these generators, see Poincaré algebra.

The \mathcal{N}=(2,2) supersymmetry algebra over this space is a supersymmetric extension of this Lie algebra with the four additional generators (supercharges) Q_+, \, Q_-, \, \overline{Q}_+, \, \overline{Q}_-, which are odd elements of the Lie superalgebra. Under Lorentz transformations the generators Q_+ and \overline{Q}_+ transform as left-handed Weyl spinors, while Q_- and \overline{Q}_- transform as right-handed Weyl spinors. The algebra is given by the Poincaré algebra plus{{Cite book|title=Mirror symmetry|date=2003|publisher=American Mathematical Society|others=Hori, Kentaro.|isbn=9780821829554|location=Providence, RI|oclc=52374327}}{{Rp|283}}

\begin{align}

&\begin{align}

&Q_+^2 = Q_{-}^2 = \overline{Q}_+^2 = \overline{Q}_-^2 =0, \\

&\{ Q_{\pm}, \overline{Q}_{\pm} \} = H \pm P, \\

\end{align} \\

&\begin{align}

&\{\overline{Q}_+, \overline{Q}_- \} = Z, && \{Q_+, Q_- \} = Z^*, \\

&\{Q_-, \overline{Q}_+ \} =\tilde{Z}, && \{Q_+, \overline{Q}_-\} = \tilde{Z}^*,\\

&{[iM, Q_{\pm}]} = \mp Q_{\pm}, && {[iM, \overline{Q}_{\pm}]} = \mp \overline{Q}_{\pm},

\end{align}

\end{align}

where all remaining commutators vanish, and Z

and \tilde{Z}

are complex central charges. The supercharges are related via Q_{\pm}^\dagger = \overline{Q}_\pm

. H

, P

, and M are Hermitian.

Subalgebras of the {{nowrap|''N''{{=}}(2,2)}} algebra

= The {{nowrap|''N''{{=}}(0,2)}} and {{nowrap|''N''{{=}}(2,0)}} subalgebras =

The \mathcal{N} = (0,2) subalgebra is obtained from the \mathcal{N} = (2,2)

algebra by removing the generators Q_- and \overline{Q}_-. Thus its anti-commutation relations are given by{{Rp|289}}

\begin{align}

&Q_+^2 = \overline{Q}_+^2 = 0, \\

&\{ Q_{+}, \overline{Q}_{+} \} = H + P \\

\end{align}

plus the commutation relations above that do not involve Q_- or \overline{Q}_-. Both generators are left-handed Weyl spinors.

Similarly, the \mathcal{N} = (2,0) subalgebra is obtained by removing Q_+ and \overline{Q}_+ and fulfills

\begin{align}

&Q_-^2 = \overline{Q}_-^2 = 0, \\

&\{ Q_{-}, \overline{Q}_{-} \} = H - P. \\

\end{align}

Both supercharge generators are right-handed.

= The {{nowrap|''N''{{=}}(1,1)}} subalgebra =

The \mathcal{N} = (1,1) subalgebra is generated by two generators Q_+^1 and Q_-^1 given by

\begin{align}

Q^1_{\pm} = e^{i \nu_{\pm}} Q_{\pm} + e^{-i \nu_{\pm}} \overline{Q}_{\pm}

\end{align}

for two real numbers \nu_+and \nu_-.

By definition, both supercharges are real, i.e. (Q_{\pm}^1)^\dagger = Q^1_\pm

. They transform as Majorana-Weyl spinors under Lorentz transformations. Their anti-commutation relations are given by{{Rp|287}}

\begin{align}

&\{ Q^1_{\pm}, Q^1_{\pm} \} = 2 (H \pm P), \\

&\{ Q^1_{+}, Q^1_{-} \} = Z^1,

\end{align}

where Z^1 is a real central charge.

= The {{nowrap|''N''{{=}}(0,1)}} and {{nowrap|''N''{{=}}(1,0)}} subalgebras =

These algebras can be obtained from the \mathcal{N} = (1,1) subalgebra by removing Q_-^1 resp. Q_+^1from the generators.

See also

References

  • K. Schoutens, Supersymmetry and factorized scattering, Nucl.Phys. B344, 665–695, 1990
  • T.J. Hollowood, E. Mavrikis, The N = 1 supersymmetric bootstrap and Lie algebras, Nucl. Phys. B484, 631–652, 1997, arXiv:hep-th/9606116

Category:Supersymmetry

Category:Mathematical physics

Category:Lie algebras