pythia8

________________________________________
From: <email address hidden> [<email address hidden>] on behalf of NADY [<email address hidden>]
Sent: 02 November 2011 14:31
To: Nady Bakhet
Subject: [Question #177259]: pythia8

New question #177259 on MadGraph5:
https://answers.launchpad.net/madgraph5/+question/177259

Dear Johan

I am very sorry for my many questions.

beacuse there are confusions with me for using of output MG5 for pythia8 matrix elements source code from one hand

and also output MG5 (LHE) and output MG5 for pythia8 matrix elements source code from other hand

according to your paper:

MadGraph 5 : Going Beyond

under topic

3.2 Matrix element libraries for Pythia 8

I did these stepes for output MG5 for pythia8 matrix elements source code for simple example :

mg5>output pythia8 /home/usr/pythia8150

1-> go to pythia8150 folder , I found the folder " Processes_sm" contains these file:

     -temp folder , HelAmps_sm.cc , HelAmps_sm , Makefile , param_card_sm.dat ,param_sm.cc,parameters_sm_h,Sigma_sm_qq_ttx.cc , sigma_sm_qq_ttx.h

2-> enter the folder " Processes_sm " and

       cd Processes_sm

            make

2-> inside examples folder i found two files main_sm_1 and Makefile_sm_1

     enter the folder examples

       cd examples

             make -f Makefile_sm_1

             this produce main_sm_1.exe ----> works very good without any problems

4->1st Question:

        How i can use the new generated library from this process in new created pythia8 file.

           means what is the syntax which i write it for use this new process inside new file [i do not want to modify the file main_sm_1 i want create new one]

5->2nd Question:

     Can I generate LHE file for this process from MG5 and use that file with pythia8 new file?

      If yes, What the difference between the using of LHE file for this process and the source code of matrix elements for the same process in Pythia8 , Is the same result ? if yes I think the using of LHE file with pythia8 is easy than the second one so whey we need the output MG5 for pythia8 matrix elements source code ,Is this useful in any thing?

once again ,Is difference in pythia8 results when i use output MG5 for pythia8 matrix elements source code and the output MG5 (LHE)file for the same process?

Finally , i can say i want to open new file in examples folder and write the syntax of new process which i craeted with MG5 as the same any internal core pythia8 processes.

Very sorry Johan for my many questions

Cheers.

Nady

--
You received this question notification because you asked the question.

Hello Nady,

You can see from the main_sm_1.cc file and the Pythia manual how to use the matrix elements created from MG5. It should be trivial to include them in the example in the rootexamples directory, since they work exactly like internal Pythia 8 matrix elements.
The difference between using event files from MG5 (and MadEvent) and using the matrix elements in Pythia 8 directly is mainly a matter of convenience. If you have new physics applications, it might be convenient to run directly in Pythia 8. You should note however that there is no dedicated MadGraph-Pythia 8 interface (where you can do jet matching e.g.) - we are working on this.

All the best,
Johan