problem in decaying particles with madspin

Asked by Aya Ismail Hosny Beshr on 2020-03-16

Hi,

I have an issue with madspin. I have generated the process : p p > X [QCD] using one of the BSM models and it is launched twice one by applying the shower=ON, the other shower=OFF (run_01, run_02). I have then tried to decay the particle X which is unstable using the madspin. I have edited the madspin_card.dat to include the following decay: X > Y Y, Y > q q~, Y > w+ w-, w+ > b~ c, w- > mu- vm~
X, Y are just symbols for unstable particles Y is for higgs. I have written this decay with different syntax and I ran the madspin over the generated events for the two runs separately, but each time it gives the following error:

Command "decay_events run_02" interrupted with error:
InvalidCmd : No matrix elements generated, check overall coupling orders
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/aya/MG5_aMC@NLO/MG5_aMC_v2_7_0/ppToh2_2HDMNLO_13TeV_1000ev_LHE/run_02_tag_2_debug.log'.
Please attach this file to your report.

I also, tried to change the spin mode several times, but unfortunately it is giving also the following error:

Command "decay_events run_02" interrupted with error:
ZeroResult : No Phase Space. Please check particle masses.

Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/aya/MG5_aMC@NLO/MG5_aMC_v2_7_0/ppToh2_2HDMNLO_13TeV_1000ev_LHE/run_02_tag_2_debug.log'.
Please attach this file to your report.

Could you kindly help me with this?

Best Regards,
Aya

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2020-03-16
Last reply:
2020-03-17

Hi,

First let me stress that MadSpin does not perform PDF re-weighting this means that it can not
correctly adapt the off-shell contribution of the X particles.
(it is not advise to run madspin on 2>1 process --even at NLO--)

After this word of caution on the precision of MadSpin,
I guess that the syntax that you are looking for is:
> decay X > Y Y, Y > q q~, (Y > w+ w-, w+ > b~ c, w- > mu- vm~)

Now to have this working it is mandatory to have
MX >> 2*MY
MY >> 2*MW
If this is not the case, you are NOT in the narrow-width regime and MadSpin is not going to work.
According to the error message that you face this sounds that this is not your case.

Cheers,

olivier

> On 16 Mar 2020, at 16:02, Aya Ismail Hosny Beshr <email address hidden> wrote:
>
> New question #689344 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/689344
>
> Hi,
>
> I have an issue with madspin. I have generated the process : p p > X [QCD] using one of the BSM models and it is launched twice one by applying the shower=ON, the other shower=OFF (run_01, run_02). I have then tried to decay the particle X which is unstable using the madspin. I have edited the madspin_card.dat to include the following decay: X > Y Y, Y > q q~, Y > w+ w-, w+ > b~ c, w- > mu- vm~
> X, Y are just symbols for unstable particles Y is for higgs. I have written this decay with different syntax and I ran the madspin over the generated events for the two runs separately, but each time it gives the following error:
>
>
> Command "decay_events run_02" interrupted with error:
> InvalidCmd : No matrix elements generated, check overall coupling orders
> Please report this bug on https://bugs.launchpad.net/mg5amcnlo
> More information is found in '/home/aya/MG5_aMC@NLO/MG5_aMC_v2_7_0/ppToh2_2HDMNLO_13TeV_1000ev_LHE/run_02_tag_2_debug.log'.
> Please attach this file to your report.
>
>
> I also, tried to change the spin mode several times, but unfortunately it is giving also the following error:
>
>
> Command "decay_events run_02" interrupted with error:
> ZeroResult : No Phase Space. Please check particle masses.
>
> Please report this bug on https://bugs.launchpad.net/mg5amcnlo
> More information is found in '/home/aya/MG5_aMC@NLO/MG5_aMC_v2_7_0/ppToh2_2HDMNLO_13TeV_1000ev_LHE/run_02_tag_2_debug.log'.
> Please attach this file to your report.
>
>
> Could you kindly help me with this?
>
> Best Regards,
> Aya
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Aya Ismail Hosny Beshr (ayaa) said : #2

ok Thanks for the information!

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