# supersymmetry

###### Definition 0.1.

Supersymmetry or Poincaré, (extended) quantum symmetry is usually defined as an extension of ordinary spacetime symmetries obtained by adjoining $N$ spinorial generators $Q$ whose anticommutator yields a translation generator: $\left\{Q,Q\right\}=\left\{P\right\}$.

As further explained in ref. [1]:

“This (super) symmetry…(of the superspace)… can be realized on ordinary fields (that are defined as certain functions of physical spacetime(s)) by transformations that mix bosons and fermions. Such realizations suffice to study supersymmetry (one can write invariant actions, etc.) but are as cumbersome and inconvenient as doing vector calculus component by component. A compact alternative to this ‘component field’ approach is given by the superspace–superfield approach”, which is defined next.

###### Definition 0.2.

Quantum superspace, or superspacetimes, can be defined as an extension(s) of ordinary spacetime(s) to include additional anticommuting coordinates, for example, in the form of $N$ two-component Weyl spinors $\theta$.

###### Definition 0.3.

(Quantum) superfields $\Psi(x,\theta)$ are functions defined over such superspaces, or superspacetimes. Taylor series expansions of the superfield functions can be then performed with respect to the anticommuting coordinates $\theta$; this Taylor series has only a finite number of terms and the series expansion coefficients obtained in this manner are the ordinary ‘component fields’ specified above.

Remarks: Supersymmetry is expected to be manifested, or observable, in such superspaces, that is, the supersymmetry algebras are represented by translations and rotations involving both the spacetime and the anticommuting coordinates. Then, the transformations of the ‘component fields’ can be computed from the Taylor expansion of the translated and rotated superfields. Especially important are those transformations that mix boson and fermion symmetries; further details are found in ref. [2].

## References

• 1 J.S. Gates, Jr, et al. “Superspace”., arxiv-hep-th/0108200 preprint (1983).
• 2 “Preprint of 1,001 Lessons in Supersymmetry.” http://arxiv.org/abs/hep-th/0108200on line PDF.
 Title supersymmetry Canonical name Supersymmetry Date of creation 2013-03-22 18:17:00 Last modified on 2013-03-22 18:17:00 Owner bci1 (20947) Last modified by bci1 (20947) Numerical id 22 Author bci1 (20947) Entry type Definition Classification msc 55U40 Classification msc 55-02 Classification msc 81Q60 Classification msc 81R50 Classification msc 81R15 Synonym extended quantum symmetry structures Synonym generalized double algebras Synonym supersymmetries Related topic QuantumAlgebraicTopology Related topic AlgebraicFoundationsOfQuantumAlgebraicTopology Related topic SuperfieldsSuperspace Related topic LieSuperalgebra3 Defines extended quantum symmetry structures Defines both local and global