Grassmann variables and Weyl spinors

In summary, when expanding the vector superfield in components, one obtains terms of the form \theta^{\alpha}\chi_{\alpha}, where \theta is a Grassmann number and \chi is a Weyl spinor component that anticommutes with other Grassmann variables. The vector superfield V describes a vector multiplet and contains a field v_{\mu} which is a spacetime vector. When calculating a commutator/anticommutator involving Grassmann numbers, use the fact that they anticommute and form an orthogonal basis for the fermionic part of superspace.
  • #1
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I just started studying supersymmetry, but I am a little bit confused with the superspace and superfield formalism. When expanding the vector superfield in components, one obtains therms of the form [itex]\theta^{\alpha}\chi_{\alpha}[/itex], where [itex]\theta[/itex] is a Grassmann number and [itex]\chi[/itex] is a Weyl vector.

I am aware that Grassmann numbers anticommute [itex]\{\theta_{\alpha},\theta_{\beta}\}=0[/itex], and that ordinary numbers commute with Grassmann variables. Do Weyl spinor components commute or anticommute with the Grassmann variables? ([itex]\{\theta_{\alpha},\chi_{\beta}\}=0[/itex] or [itex][\theta_{\alpha},\chi_{\beta}]=0[/itex]).
 
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  • #2
Weyl spinor components are Grassman variables. As such they anticommute with other Grassman variables.

I'm not sure why you call the chi a "Weyl vector". The vector superfield V is not a vector, but it describes a vector multiplet and as such contains a field [itex]v_{\mu}[/itex] which is a spacetime vector.
 
  • #3
Hi!
I have a similar problem: what is the result of a commutator/anticommutator like this?
[itex]\left\{ \left( \gamma^{\mu} \theta \right)_{\alpha} \partial_{\mu} , \frac{\partial}{\partial \bar{\theta}^{\beta} } \right\}[/itex]
Thank you
 
  • #4
Use that the theta's (both the parameters and derivatives wrt them) anticommute and form an orthogonal basis for the fermionic part of superspace.
 

Related to Grassmann variables and Weyl spinors

1. What are Grassmann variables and how are they used in physics?

Grassmann variables are mathematical objects used to describe fermionic degrees of freedom in quantum field theory. They are anti-commuting variables, meaning that their product changes sign when the order is swapped. In physics, they are used to describe spin 1/2 particles, such as electrons, and their interactions with other particles.

2. How are Grassmann variables related to Weyl spinors?

Weyl spinors are a type of fermionic field that describes spin 1/2 particles in quantum field theory. Grassmann variables are used to construct these fields, with each Grassmann variable corresponding to a different spinor component. Weyl spinors are important in theories such as the Standard Model of particle physics.

3. What is the significance of the anti-commuting nature of Grassmann variables?

The anti-commuting nature of Grassmann variables is essential for describing fermionic degrees of freedom in quantum field theory. Without this property, the mathematics of quantum field theory would not accurately reflect the behavior of fermions, leading to incorrect predictions. It also allows for the use of powerful mathematical tools, such as path integrals, in the study of these systems.

4. Can Grassmann variables be visualized or understood geometrically?

Grassmann variables have no direct physical interpretation or geometric representation. They are purely mathematical objects that are used to describe fermionic degrees of freedom in quantum field theory. However, they can be thought of as analogous to the concept of anti-commuting numbers, which can be visualized as vectors in a higher-dimensional space.

5. How are Grassmann variables and Weyl spinors used in supersymmetry?

Supersymmetry is a theoretical framework that extends the Standard Model of particle physics by introducing a new symmetry between fermions and bosons. Grassmann variables and Weyl spinors play a crucial role in this theory, as they are used to describe the superpartners of known particles. These superpartners have not yet been observed experimentally, but their existence is predicted by supersymmetry.

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