I don't have pstricks...so I am going to use words.(adsbygoogle = window.adsbygoogle || []).push({});

[tex]

\text{contraction}\{ \overline{\psi}(x_1) \psi(x_1) \}

[/tex]

My question: Propogators are usually dealing with different points...but what is the contraction of two quantities evaluated at the same point.

Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Dirac Contraction

**Physics Forums | Science Articles, Homework Help, Discussion**