running pythia8

Asked by Juhi Dutta

Hi,

I am using MG5_aMC_v2_2_3 .I am generating p p > t t~ and want to interface pythia8.205 version along with mg5. I set the pythia8 path appropriately ( pythia8_path = /home/juhi/pythia8205 ) in the MG5_aMC_v2_2_3/input/mg5_configuration.txt and then generated a process as follows:

generate p p > t t~
output pythia8 /home/juhi/pythia8205

A warning at this stage : WARNING: Directory /home/juhi/pythia8205 is not a valid Pythia 8 main dir.

However it goes on to produce Processes_sm and examples folder in the pythia8205 directory. After which I do the following:

cd Processes_sm
make

This stops with an error : make: *** No rule to make target `../config.mk', needed by `all'. Stop.

I enter the examples directory which has 2 files main_sm_1.cc and Makefile_sm_1. and did the following :

make -f Makefile_sm_1

This encounters an error : make: *** No rule to make target `../config.mk', needed by `all'. Stop.

Do I need to make any changes elsewhere in the madgraph5/pythia8205 code elsewhere ?

Also I referred to the MG5 manual and the following answers on launchpad : https://answers.launchpad.net/mg5amcnlo/+question/256707 and https://answers.launchpad.net/mg5amcnlo/+question/177259 for help but the error remains.

Kindly advise me in this regard.

Thanks & Regards,

Juhi

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Olivier Mattelaer (olivier-mattelaer) said :
#1

Dear Juhi,

The mode “output pythia8” is created to import inside pythia8 processes (especially BSM ones) which are not supported natively in py8.
I’m pretty sure p p >t t~ (in the SM) is present.

I guess that you are more interested by generating events in MG (likely with decay to have full spin-correlation) and then pass those to PY8?
We do not have a built-in interface to PY8, so you just have to take the LHE event file, and pass it to pythia8 via what they call the LHEF interface.

Cheers,

Olivier

On 31 May 2015, at 17:31, Juhi Dutta <email address hidden> wrote:

> New question #267603 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/267603
>
> Hi,
>
> I am using MG5_aMC_v2_2_3 .I am generating p p > t t~ and want to interface pythia8.205 version along with mg5. I set the pythia8 path appropriately ( pythia8_path = /home/juhi/pythia8205 ) in the MG5_aMC_v2_2_3/input/mg5_configuration.txt and then generated a process as follows:
>
> generate p p > t t~
> output pythia8 /home/juhi/pythia8205
>
> A warning at this stage : WARNING: Directory /home/juhi/pythia8205 is not a valid Pythia 8 main dir.
>
> However it goes on to produce Processes_sm and examples folder in the pythia8205 directory. After which I do the following:
>
> cd Processes_sm
> make
>
> This stops with an error : make: *** No rule to make target `../config.mk', needed by `all'. Stop.
>
> I enter the examples directory which has 2 files main_sm_1.cc and Makefile_sm_1. and did the following :
>
> make -f Makefile_sm_1
>
> This encounters an error : make: *** No rule to make target `../config.mk', needed by `all'. Stop.
>
> Do I need to make any changes elsewhere in the madgraph5/pythia8205 code elsewhere ?
>
> Also I referred to the MG5 manual and the following answers on launchpad : https://answers.launchpad.net/mg5amcnlo/+question/256707 and https://answers.launchpad.net/mg5amcnlo/+question/177259 for help but the error remains.
>
> Kindly advise me in this regard.
>
> Thanks & Regards,
>
> Juhi
>
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Juhi Dutta (dutta-juhi91) said :
#2

Hi,

I want to generate events in MG5 and shower them using Pythia8 . I further
wanted to generate ttbar upto 2 jets at NLO order using aMCatNLO in MG5 .
Here I see that the merging procedure to avoid double counting is available
only using Pythia8 showers (and Herwig showers but I want to use Pythia8
preferably). Yes Standalone Pythia8 does have ttbar process inbuilt.But I
am not sure if they allow NLO level computations using matching and merging
as in aMCatNLO.

Also I tried generating p p > go go in MG5 and followed the steps for
outputting in pythia8 as before but am getting the same error. Am I going
wrong with the syntax some where?

Thanks & Regards,

Juhi

On Mon, Jun 1, 2015 at 4:16 AM, Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #267603 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/267603
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Dear Juhi,
>
> The mode “output pythia8” is created to import inside pythia8 processes
> (especially BSM ones) which are not supported natively in py8.
> I’m pretty sure p p >t t~ (in the SM) is present.
>
> I guess that you are more interested by generating events in MG (likely
> with decay to have full spin-correlation) and then pass those to PY8?
> We do not have a built-in interface to PY8, so you just have to take the
> LHE event file, and pass it to pythia8 via what they call the LHEF
> interface.
>
> Cheers,
>
> Olivier
>
>
> On 31 May 2015, at 17:31, Juhi Dutta
> <email address hidden> wrote:
>
> > New question #267603 on MadGraph5_aMC@NLO:
> > https://answers.launchpad.net/mg5amcnlo/+question/267603
> >
> > Hi,
> >
> > I am using MG5_aMC_v2_2_3 .I am generating p p > t t~ and want to
> interface pythia8.205 version along with mg5. I set the pythia8 path
> appropriately ( pythia8_path = /home/juhi/pythia8205 ) in the
> MG5_aMC_v2_2_3/input/mg5_configuration.txt and then generated a process as
> follows:
> >
> > generate p p > t t~
> > output pythia8 /home/juhi/pythia8205
> >
> > A warning at this stage : WARNING: Directory /home/juhi/pythia8205 is
> not a valid Pythia 8 main dir.
> >
> > However it goes on to produce Processes_sm and examples folder in the
> pythia8205 directory. After which I do the following:
> >
> > cd Processes_sm
> > make
> >
> > This stops with an error : make: *** No rule to make target `../
> config.mk', needed by `all'. Stop.
> >
> > I enter the examples directory which has 2 files main_sm_1.cc and
> Makefile_sm_1. and did the following :
> >
> > make -f Makefile_sm_1
> >
> > This encounters an error : make: *** No rule to make target `../
> config.mk', needed by `all'. Stop.
> >
> > Do I need to make any changes elsewhere in the madgraph5/pythia8205 code
> elsewhere ?
> >
> > Also I referred to the MG5 manual and the following answers on launchpad
> : https://answers.launchpad.net/mg5amcnlo/+question/256707 and
> https://answers.launchpad.net/mg5amcnlo/+question/177259 for help but the
> error remains.
> >
> > Kindly advise me in this regard.
> >
> > Thanks & Regards,
> >
> > Juhi
> >
> >
> >
> > --
> > You received this question notification because you are an answer
> > contact for MadGraph5_aMC@NLO.
>
> --
> If this answers your question, please go to the following page to let us
> know that it is solved:
>
> https://answers.launchpad.net/mg5amcnlo/+question/267603/+confirm?answer_id=0
>
> If you still need help, you can reply to this email or go to the
> following page to enter your feedback:
> https://answers.launchpad.net/mg5amcnlo/+question/267603
>
> You received this question notification because you asked the question.
>

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said :
#3

Hi,

As I said the command "output pythia8" is only to generate code to make the computation internally to pythia8.
This is clearly not what you are looking for.

At leading order, we do not have an automatic interface to pythia8.
So for those generation, you need to do:
import model mssm
generate p p > go go
output
launch
and then use the generate events and run py8 manually.

On the otherhand, At NLO we have an automatic interface.

Cheers,

Olivier

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