---
title: "Supersymmetry"
chunk: 6/6
source: "https://en.wikipedia.org/wiki/Supersymmetry"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:40:45.384774+00:00"
instance: "kb-cron"
---

=== Extended supersymmetry ===
It is possible to have more than one kind of supersymmetry transformation. Theories with more than one supersymmetry transformation are known as extended supersymmetric theories. The more supersymmetry a theory has, the more constrained are the field content and interactions. Typically the number of copies of a supersymmetry is a power of 2 (1, 2, 4, 8...). In four dimensions, a spinor has four degrees of freedom and thus the minimal number of supersymmetry generators is four in four dimensions and having eight copies of supersymmetry means that there are 32 supersymmetry generators.
The maximal number of supersymmetry generators possible is 32. Theories with more than 32 supersymmetry generators automatically have massless fields with spin greater than 2. It is not known how to make massless fields with spin greater than two interact, so the maximal number of supersymmetry generators considered is 32. This is due to the Weinberg–Witten theorem. This corresponds to an N = 8 supersymmetry theory. Theories with 32 supersymmetries automatically have a graviton.
For four dimensions there are the following theories, with the corresponding multiplets (CPT adds a copy, whenever they are not invariant under such symmetry):

=== Supersymmetry in alternate numbers of dimensions ===
It is possible to have supersymmetry in dimensions other than four. Because the properties of spinors change drastically between different dimensions, each dimension has its characteristic. In d dimensions, the size of spinors is approximately 2d/2 or 2(d−1)/2. Since the maximum number of supersymmetries is 32, the greatest number of dimensions in which a supersymmetric theory can exist is eleven.

=== Fractional supersymmetry ===
Fractional supersymmetry is a generalization of the notion of supersymmetry in which the minimal positive amount of spin does not have to be ⁠1/2⁠ but can be an arbitrary ⁠1/N⁠ for integer value of N. Such a generalization is possible in two or fewer spacetime dimensions.

== See also ==

== References ==

== Further reading ==

=== Theoretical introductions, free and online ===

=== Monographs ===

=== On experiments ===

== External links ==

Supersymmetry – European Organization for Nuclear Research (CERN)
The status of supersymmetry – Symmetry Magazine (Fermilab/SLAC), January 12, 2021
As Supersymmetry Fails Tests, Physicists Seek New Ideas – Quanta Magazine, November 20, 2012
What is Supersymmetry? – Fermilab, May 21, 2013
Why Supersymmetry? – Fermilab, May 31, 2013
The Standard Model and Supersymmetry – World Science Festival, March 4, 2015
SUSY running out of hiding places – BBC, December 11, 2012