Version 2 (modified by omatt, 7 years ago) (diff) |
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# I have zero result Why?

## Typical reasons

- A massive s-channel particle has a width set to zero.
- The pdf are zero for at least one of the initial state particles.
- The cuts are too strong.
- For decay computation the mass of the final state is larger than the mass of the initial state.

Please take a look at your Cards (param_card/ run_card)

## More particular reason

In presence of 4 point interactions and if you have diagram with 3 point interaction but that the coupling are such that all 3 point interaction are zero, MG can fail to integrate the 4 point interactions. We advice you to use a restricted model whithout those superfluous 3 point interactions and MG will integrate correctly the 4 point interaction diagram.