MadGraph5_aMC@NLO

outgoing proton simulation in photon collisions

Asked by LIGANG XIA

Dear MG team,

 I would like to simulate photon photon collisions using proton proton beams. I use the heft model, set lpp1,lpp2 = 2 and have enerated some events for the process

a a > b b~.

It contains the QED diagrams and the Higgs diagram as expected. This is good. But I do not find the information on the output protons. For example, one LHE event is

 <event>
  4 1 +7.2297395e-01 1.61997000e+01 7.54677100e-03 1.83352300e-01
        22 -1 0 0 0 0 +0.0000000000e+00 +0.0000000000e+00 +4.0608143345e+00 4.0608143345e+00 0.0000000000e+00 0.0000e+00 1.0000e+00
        22 -1 0 0 0 0 -0.0000000000e+00 -0.0000000000e+00 -2.5735047744e+02 2.5735047744e+02 0.0000000000e+00 0.0000e+00 -1.0000e+00
         5 1 1 2 501 0 -1.2052858925e+01 +9.7503301532e+00 -1.3534737776e+01 2.1109700922e+01 4.7000000000e+00 0.0000e+00 1.0000e+00
        -5 1 1 2 0 501 +1.2052858925e+01 -9.7503301532e+00 -2.3975492533e+02 2.4030159085e+02 4.7000000000e+00 0.0000e+00 -1.0000e+00
 <mgrwt>
 <rscale> 0 0.16199702E+02</rscale>
 <asrwt>0</asrwt>
 <pdfrwt beam="1"> 1 22 0.62474061E-03 0.16199702E+02</pdfrwt>
 <pdfrwt beam="2"> 1 22 0.39592385E-01 0.16199702E+02</pdfrwt>
 <totfact> 0.98060241E+01</totfact>
 </mgrwt>
 </event>

I understand that the outgoing protons are very close to the beam direction and most of them will not be detected by the trackers and calorimeters. But I would like to look at the rare cases where the outgoing protons DO go into the detectors. Is it possible to add the proton information (and simulate within some detectors using Delphes)?

Thanks a lot!

Best regards,
Ligang

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MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Dear Ligang,

Adding the information withing the lhef output is in principle trivial. We do not have that automated, but it just a mattter to add information into that file (i.e. you should be able to do it yourself).

Now the issue is how the parton-shower code will handle such additional information. For that you should contact the author of the parton-shower that you plan to use. They will be able to tell you how exactly such information should be written in the lhef (or they might indicate that it is maybe better to include that in hepmc output directly by hacking that file.

Once you have that information inside the hepmc file, I believe that it should be fine for Delphes to handle this (but might be better to check with them).

Cheers,

Olivier

Revision history for this message
LIGANG XIA (xialigang) said : 		#2

Thanks Olivier Mattelaer, that solved my question.