MadGraph5_aMC@NLO

Long-lived particles in LHEF with zero lifetime

Asked by Nishita

Dear Madgraph authors,

I have a question regarding how LHE files are written when unstable particles are produced (to be decayed later with Pythia 8). The lifetime field in the LHE file is by default set to zero even for particles with very small width. This is usually okay but not for long-lived ones because even though Pythia reads the proper lifetime from the decay table, each particle is still decayed promptly because the kinematics from LHE says so. Would it be possible to get MG5 to write the actual lifetime in the LHE file?

Thanks.

Best,
Nishita.

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

You have an entry of the run_card for doing that.
You can also run the post-processing script which write those information via the
./bin/madevent interface (or launch -i from the mg5_aMC prompt)
The command is add_time_of_flight
You can find the required argument by typing "help add_time_of_flight” (in that interface)

Cheers,

Olivier

> On 27 Jan 2017, at 12:14, Nishita <email address hidden> wrote:
>
> New question #447844 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/447844
>
> Dear Madgraph authors,
>
> I have a question regarding how LHE files are written when unstable particles are produced (to be decayed later with Pythia 8). The lifetime field in the LHE file is by default set to zero even for particles with very small width. This is usually okay but not for long-lived ones because even though Pythia reads the proper lifetime from the decay table, each particle is still decayed promptly because the kinematics from LHE says so. Would it be possible to get MG5 to write the actual lifetime in the LHE file?
>
> Thanks.
>
> Best,
> Nishita.
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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