Decay chain with loop diagram

Asked by Youying on 2017-01-05

Hi,

I want to generate the loop diagram in decay chain like higgs to two photons in higgs productions. Although I know in Madgraph5 that is not allowed, I still want to do this. How can I do ?

Thanks
Youying

Question information

Language:
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Status:
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MadGraph5_aMC@NLO Edit question
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Last query:
2017-01-06
Last reply:
2017-01-06

Hi,

This is explained in paper: arXiv:1507.00020

In that case, you have to use madspin within a special mode: “set spinmode none”

Cheers,

Olivier

> On Jan 5, 2017, at 05:53, Youying <email address hidden> wrote:
>
> New question #429612 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/429612
>
> Hi,
>
> I want to generate the loop diagram in decay chain like higgs to two photons in higgs productions. Although I know in Madgraph5 that is not allowed, I still want to do this. How can I do ?
>
>
> Thanks
> Youying
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Youying (youying) said : #2

Hi,

I do a test. I generate higgs production via vbf and the higgs decay to diphoton. The following is my work flow:

./bin/mg5_aMC

generate p p > h j j

output myfile

cd myfile

./bin/generate_events

I open madspin_card.dat and add these two lines:

set spinmode none

decay h > a a [virt=QED]

Then just run.

However, the system tell me

Command "generate_events " interrupted with error:
Exception : ['bin/internal/gen_cardhtml-pl'] fails with no such file or directory

Do I make some mistakes?

On the other hand, if I succeed getting this process, can these two photon information (P4, PID,...) record in LHE files which let me run the pythia8 ?

Thanks
Youying

Hi,

> Command "generate_events " interrupted with error:
> Exception : [‘bin/internal/gen_cardhtml-pl'] fails with no such file or directory

1) Which version of the code did you use?
2) Do you have the file myfile/bin/internal/gen_cardhtml-pl
3) Do you have the script /usr/bin/perl on your machine

> I open madspin_card.dat and add these two lines:
>
> set spinmode none
>
> decay h > a a [virt=QED]

You also need to tell madspin to use another model (in this case loop_qcd_qed_sm)
here is the syntax(https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/MadSpin):
import model ModelNane ParamCardPath

Cheers,

Olivier

> On Jan 5, 2017, at 13:13, Youying <email address hidden> wrote:
>
> Question #429612 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/429612
>
> Status: Answered => Open
>
> Youying is still having a problem:
> Hi,
>
> I do a test. I generate higgs production via vbf and the higgs decay to
> diphoton. The following is my work flow:
>
> ./bin/mg5_aMC
>
> generate p p > h j j
>
> output myfile
>
> cd myfile
>
> ./bin/generate_events
>
> I open madspin_card.dat and add these two lines:
>
> set spinmode none
>
> decay h > a a [virt=QED]
>
> Then just run.
>
> However, the system tell me
>
> Command "generate_events " interrupted with error:
> Exception : ['bin/internal/gen_cardhtml-pl'] fails with no such file or directory
>
> Do I make some mistakes?
>
> On the other hand, if I succeed getting this process, can these two
> photon information (P4, PID,...) record in LHE files which let me run
> the pythia8 ?
>
> Thanks
> Youying
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Youying (youying) said : #4

Hi,

Thanks for your help.
I add "import model ModelNane ParamCardPath --bypass_check]" in my madspin_card.dat.

I use MG5_aMC_v2.5.2 and I'm sure I have these two files in my machine.
But the system still tell me:

 Command "generate_events " interrupted with error:
 Exception : [‘bin/internal/gen_cardhtml-pl'] fails with no such file or directory

Is this a bug?

Thanks
Youying

Hi,

Yeah this is a bug, which is somehow connected to your environment since I can not reproduce it.

Can you copy paste the content of the debug file?

Cheers,

olivier

> On Jan 6, 2017, at 04:03, Youying <email address hidden> wrote:
>
> Question #429612 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/429612
>
> Status: Answered => Open
>
> Youying is still having a problem:
> Hi,
>
> Thanks for your help.
> I add "import model ModelNane ParamCardPath --bypass_check]" in my madspin_card.dat.
>
> I use MG5_aMC_v2.5.2 and I'm sure I have these two files in my machine.
> But the system still tell me:
>
> Command "generate_events " interrupted with error:
> Exception : [‘bin/internal/gen_cardhtml-pl'] fails with no such file or directory
>
> Is this a bug?
>
> Thanks
> Youying
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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