Using smatrix function in standalone mode ?
Hi,
Is there a tutorial somewhere on how to use the
standalone version of MadGraph 4 or 5 because I didn't perfectly
understood the input of the smatrix function, of other function in C++
mode ?
Thanks for your help,
Tristan
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- Last query:
- 2011-06-30
- Last reply:
- 2011-06-30
This output is mainly foreseen for theorist and for interface to external program.
In order to have an example of code.
You can do
cd SubProcesses/
make
./check
The program will return the square matrix element for a hard-coded phase-space point.
You can take a look at the file check_sa.f
This contains the driver and therefore the different step needed to configure the parameter,
the format for the 4 momentum, and how to call the square matrix element.
To be more precise, in fortran the Smatrix takes two argument:
1) P which are the momentum of the different particles
define as REAL*8 P(0:3,NEXTERNAL)
2) MATELEM which is in fact the output value (and therefore is a real*8)
Maybe if we knows what you plan to do, we can provide to you a bit more help.
Cheers,
Olivier
Tristan Beau (beau-3) said : | #2 |
Ok, thanks. I didn't have a look to that check_sa source file. It's enough to understand how to call the matrix element function.
But one other related question. Is it possible to have a standalone version version including the management of pdf throw for example the lhapdf library, just like madevent can do ?
Thanks very much.
Cheers,
Tristan
Johan Alwall (johan-alwall) said : | #3 |
Hello Tristan,
The Standalone package is meant as a minimal output, including only
what's necessary to calculate the matrix element. For ideas about how
to use PDFs with the matrix elements, I would recommend to look at the
MadEvent output code (in particular auto_dsigN.
link this output to your private phase space integration code.
All the best,
Johan
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