Hi Kasper,

How can I tell cadabra2 about the \gamma*{5} matrix? If I declare it to be ::GammaMatrix, then it mixes with the other \gamma*{\mu} when I run join*gamma(*) and sort*spinors(*).

Thanks!

0 votes

If you're working on four dimensions, $\gamma^5$ is proportional to the product of the four (elemental) gamma's. Therefore you can define something like

```
{s,r,l,k,m,n,p}::Indices(vector);
{s,r,l,k,m,n,p}::Integer(0..3);
\Gamma_{#}::GammaMatrix(metric=\delta);
e_{\mu\nu\lambda\rho}::EpsilonTensor(delta=\delta);
\delta_{m n}::KroneckerDelta;
g5 := e_{l m n p} \Gamma^{l m n p};
```

You have to normalise this definition accordingly.

Remember that *Cadabra* has a definition for the imaginary number

```
i::ImaginaryI;
```

...