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{{Short description|Term in supersymmetric theories}}
{{refimprove|date=December 2024}}
In [[theoretical physics]], the '''D-term''' is the final term in the expansion of a [[vector superfield]] over [[fermionic]] coordinates. A superfield is a field that depends on all coordinates of the [[superspace]], which is the coordinate space of a theory exhibiting [[supersymmetry]].

A superspace can be expressed as a combination of ordinary space dimensions (x, y, z, ...,) and fermionic dimensions. [[4D N = 1 global supersymmetry]] may be written using a superspace involving four extra fermionic coordinates <math>\theta^1,\theta^2,\bar\theta^1,\bar\theta^2</math>, transforming as a two-component [[spinor]] and its conjugate. Every superfield may be expanded with respect to the new fermionic coordinates. The generic kind of superfields, typically a [[vector superfield]], indeed depend on all these coordinates. The last term in the corresponding expansion, namely <math>D \theta^1\theta^2\bar\theta^1\bar\theta^2</math>, is called the D-term.

Manifestly supersymmetric [[Lagrangian (field theory)|Lagrangian]]s may also be written as [[integral]]s over the whole superspace. A D-term obtained from a vector superfield solely by an integral over all of superspace is known as a [[Fayet–Iliopoulos D-term]]. Some special terms, such as the [[superpotential]], may be written as integrals over <math>\theta</math>s only, which are known as [[F-term]]s, and should be contrasted with the present D-terms.

==See also==
* [[F-term]]
* [[Supersymmetric gauge theory]]

==References==
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[[Category:Supersymmetric quantum field theory]]

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