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 -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:
is the generator of the time translation,
is the generator of the space translation,
- is the generator of Lorentz boosts.
For the commutators between these generators, see Poincaré algebra.
The supersymmetry algebra over this space is a supersymmetric extension of this Lie algebra with the four additional generators (supercharges) , which are odd elements of the Lie superalgebra. Under Lorentz transformations the generators and transform as left-handed Weyl spinors, while and 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}
&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
and
are complex central charges. The supercharges are related via
.
,
, and are Hermitian.
Subalgebras of the {{nowrap|''N''{{=}}(2,2)}} algebra
= The {{nowrap|''N''{{=}}(0,2)}} and {{nowrap|''N''{{=}}(2,0)}} subalgebras =
The subalgebra is obtained from the
algebra by removing the generators and . 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 or . Both generators are left-handed Weyl spinors.
Similarly, the subalgebra is obtained by removing and 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 subalgebra is generated by two generators and 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 and .
By definition, both supercharges are real, i.e.
. 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 is a real central charge.
= The {{nowrap|''N''{{=}}(0,1)}} and {{nowrap|''N''{{=}}(1,0)}} subalgebras =
These algebras can be obtained from the subalgebra by removing resp. from 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