Dirac algebra (contraction gamma matrices)

In summary, the conversation is about a person's search for a general formula involving the product of two gamma matrices with different types of indices. They mention having trouble deriving or intuiting the formula and are curious about the reason for the mixed indices. Another person then suggests that the formula may be related to Fierz identities, which express the product of two Dirac matrices in terms of matrices in the crossed channel. They provide a link for further reading on the topic.
  • #1
IRobot
87
0
I would like to have a general formula, and I am quite sure it must exist, for: [itex]\gamma^{\mu}_{ab}\gamma_{\mu \,\alpha\beta}[/itex] but I didn't succeed at deriving it, or intuiting it, I am troubled by the fact that it must mix dotted and undotted indices.
 
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  • #2
Why does it have different type of indices ?
 
  • #3
Because the first gamma matrix is sandwiched between two spinors.
 
  • #4
IRobot, I think what you are referring to are the Fierz identities, which express the product of two Dirac matrices in terms of matrices in the crossed channel. That is, (γμ)abμ)cd expressed in terms of (γμ)adμ)bc. See http://gemma.ujf.cas.cz/~brauner/files/Fierz_transform.pdf for an exhaustive treatment!
 

Related to Dirac algebra (contraction gamma matrices)

What is Dirac algebra?

Dirac algebra is a mathematical framework used to describe the behavior of spin-1/2 particles in quantum mechanics. It involves the use of gamma matrices, which are 4x4 matrices that represent the spin and position of particles.

What are gamma matrices?

Gamma matrices are 4x4 matrices used in Dirac algebra to represent the spin and position of particles. They are denoted by the Greek letter gamma (γ) and are used to create spinors, which are mathematical objects that describe the spin state of particles.

What is the significance of contraction in Dirac algebra?

In Dirac algebra, contraction refers to the process of multiplying gamma matrices to simplify mathematical expressions. By contracting multiple gamma matrices, complex equations can be reduced to simpler forms, making it easier to solve problems in quantum mechanics.

How is Dirac algebra used in quantum mechanics?

Dirac algebra is used in quantum mechanics to describe the behavior of spin-1/2 particles, such as electrons and protons. It allows scientists to calculate the properties of these particles, including their spin and position, and to make predictions about their behavior in various physical systems.

How does Dirac algebra relate to the Dirac equation?

The Dirac equation is a fundamental equation in quantum mechanics that describes the behavior of fermions, or particles with half-integer spin. It is based on Dirac algebra and uses gamma matrices to represent the spin and position of particles. The Dirac equation has been successful in predicting the behavior of particles in various physical systems, including atoms and subatomic particles.

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