FeynCalc manual (development version)

SUNFierz

SUNFierz[exp, {i, j, k, l}] applies Fierz identity to the product of two Kronecker deltas the in fundamental representation (SUNFDelta) carrying indices i, j, k and l present in exp.

See also

Overview, SUNSimplify, SUNT, SUNTF, SUNFDelta.

Examples

```mathematica SUNFDelta[i, j] SUNFDelta[k, l]

SUNFierz[%, {i, j, k, l}, SUNIndexNames -> {a}]

```mathematica

$$\delta _{ij} \delta _{kl}$$

$$2 T_{il}^a T_{kj}^a+\frac{\delta _{il} \delta _{jk}}{N}$$