# is subdecay of three particles possible?

Asked by pietro govoni on 2018-05-17

when trying to generate the following LO process:

generate p p > w+ w- z / h, (w+ > q q, w- > lep nus, z > b b~) QED=6 QCD=0

I get the error message that:

WARNING: Decay without corresponding particle in core process found.
Decay information for particle(s) w+,z is discarded.
This warning usually means that you forgot parentheses in presence of subdecay.
Example of correct syntax: p p > t t~, ( t > w+ b, w+ > l+ vl)

Does this mean that more than two subdecays cannot be listed in parentheses, or am I missing something else?

Best regards,

pietro

## Question information

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Solved by:
Olivier Mattelaer
Solved:
2018-05-18
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2018-05-18
2018-05-17
 pietro govoni (pietro.govoni) said on 2018-05-17: #1

I understood what I was doing wrong, I am not interested in subsequent decays in fact.
I would like to pilot the decay of each of the particles produced in the first decay; do I have to do it with madspin?

 Olivier Mattelaer (olivier-mattelaer) said on 2018-05-17: #2

Hi Pietro,

In this case you should not have any paranthesis

generate p p > w+ w- z / h QCD=0, w+ > q q, w- > lep nus, z > b b~

Cheers,

Olivier
> On 17 May 2018, at 18:22, pietro govoni <email address hidden> wrote:
>
> Question #669191 on MadGraph5_aMC@NLO changed:
>
> I understood what I was doing wrong, I am not interested in subsequent decays in fact.
> I would like to pilot the decay of each of the particles produced in the first decay; do I have to do it with madspin?
>
> --