MadGraph5_aMC@NLO

How to run MG with Herwig7

Asked by Carl Niblaeus

Hi,

Is it possible to do showering and hadronisation with Herwig7 within MadGraph? It seems possible from the info I find when I search but I can't figure out how to do it. I have Herwig7 installed through the bootstrap script in my home directory (and ThePEG and HepMC also in the same directory through the bootstrap script).

I've tried modifying input/mg5_configuration.txt to include the path to Herwig in hwpp_path, thepeg_path and hepmc_path, following the instruction to use the same directory also for ThePEG and HepMC (I also tried providing the separate directories), but without any success. When I generate events the only options for the shower variable are Pythia8 (which runs successfully) or OFF (I had expectet Herwig to appear as an option there).

I've used the path /home/[username]/Herwig7 for hwpp_path, thepeg_path and hepmc_path. The Herwig7 folder in turn contains folders like bin, src, include etc where the code for Herwig, ThePEG and HepMC can be found, and I've also tried using paths like /home/[username]/Herwig7/src or similar.

By the way, when I've searched for ways to solve the issue I've seen references to a shower_card.dat that seems to be generated for each run. However, I don't get such a card when I do a run. Is that something which has changed in the most recent version or something wrong with my installation?

Lastly, I have been able to read in the LHE file generated from a MG run into Herwig7 and do the shower/hadronisation there with success. However, I would prefer if I could do everything from within MG.

I'm using MG5 v2.6.3.2 downloaded some weeks ago.

Thankful for any help,
Carl

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Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

I guess that you are running at LO accuracy.
For such type of generation we do not have an on the flight interface to Herwig7 working.
(The main issue of creating such interface is to support correctly all the matching/merging method)

For NLO generation, we do have such link to HW7 (even if I have personally never test it)
--without support for FxFx or other type of merging method--
and indeed in that case, the interface use a standard shower_card.dat

> Lastly, I have been able to read in the LHE file generated from a MG run into Herwig7 and do the shower/hadronisation there with success. However, I would prefer if I could do everything from within MG.

I agree that it would be nice but this is not top priority for the moment.

Cheers,

Olivier

> On 19 Sep 2018, at 15:43, Carl Niblaeus <email address hidden> wrote:
>
> New question #674140 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/674140
>
> Hi,
>
> Is it possible to do showering and hadronisation with Herwig7 within MadGraph? It seems possible from the info I find when I search but I can't figure out how to do it. I have Herwig7 installed through the bootstrap script in my home directory (and ThePEG and HepMC also in the same directory through the bootstrap script).
>
> I've tried modifying input/mg5_configuration.txt to include the path to Herwig in hwpp_path, thepeg_path and hepmc_path, following the instruction to use the same directory also for ThePEG and HepMC (I also tried providing the separate directories), but without any success. When I generate events the only options for the shower variable are Pythia8 (which runs successfully) or OFF (I had expectet Herwig to appear as an option there).
>
> I've used the path /home/[username]/Herwig7 for hwpp_path, thepeg_path and hepmc_path. The Herwig7 folder in turn contains folders like bin, src, include etc where the code for Herwig, ThePEG and HepMC can be found, and I've also tried using paths like /home/[username]/Herwig7/src or similar.
>
> By the way, when I've searched for ways to solve the issue I've seen references to a shower_card.dat that seems to be generated for each run. However, I don't get such a card when I do a run. Is that something which has changed in the most recent version or something wrong with my installation?
>
> Lastly, I have been able to read in the LHE file generated from a MG run into Herwig7 and do the shower/hadronisation there with success. However, I would prefer if I could do everything from within MG.
>
> I'm using MG5 v2.6.3.2 downloaded some weeks ago.
>
> Thankful for any help,
> Carl
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Carl Niblaeus (cnibl) said : 		#2

Thanks Olivier Mattelaer, that solved my question.

Revision history for this message
Nenad Vranjes (nsvranjes) said : 		#3

I would like to revive this question: is there now a working interface to Herwig7? For example one wants to compare MG+PY8 and MG+Herwig7 at LO accuracy for a given process. If the answer is yes, could you provide some details.

Thanks you in advance, cheers,
Nenad

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#4

Hi,

For MadEvent, we do not have any interface in place.
Now you can generate/use the NLO code and run at LO accuracy.
And there you should be able to run both parton shower via the unique shower_card.dat.

I have personally never run in that way, so be prudent, but in principle this should work.

Cheers,

Olivier

> On 4 Feb 2022, at 10:50, Nenad Vranjes <email address hidden> wrote:
>
> Question #674140 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/674140
>
> Nenad Vranjes posted a new comment:
> I would like to revive this question: is there now a working interface
> to Herwig7? For example one wants to compare MG+PY8 and MG+Herwig7 at
> LO accuracy for a given process. If the answer is yes, could you provide
> some details.
>
> Thanks you in advance, cheers,
> Nenad
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Nenad Vranjes (nsvranjes) said : 		#5

Hi,

Many thanks! This is useful.

Cheers,
Nenad

Revision history for this message
Subhojit Roy (subhojitroy) said : 		#6

Hi,

I am revisiting this matter once again.

I am incorporating the NL0 effect by utilizing loop_sm.
Could you please guide me on the necessary modifications in the shower_card.py file, if needed.
I am unable to locate the shower_card.dat file. Where can I find it?
Additionally, could you kindly instruct me on running the parton shower through Herwig and establishing an interface between Herwig and MadGraph.

Cheers,
Subhojit

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#7

Hi,

I guess that you are confusing "loop-induced" process which involves a single power of alpha_strong and therefore run as a a leading order computation (and therefore no shower_card.dat) with a normal NLO computation (which involves two power of alpa_s, one for the born and one more power for the real and virtual), where we do have shower_card.dat

> Additionally, could you kindly instruct me on running the parton shower through Herwig and establishing an interface between Herwig and MadGraph.

Sorry I have no experience in running Herwig shower. So I will not be able to provide instruction.