MadGraph5_aMC@NLO

return 0 for photon when using pdf containing photon

Bug #1131995 reported by Olivier Mattelaer
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
MadGraph5_aMC@NLO
Fix Released
Wishlist
Olivier Mattelaer

Bug Description

Bug reported By Marc-Andre Pleier,

I tried to generate a a > W+ W-
   using photon pdfs and get a result. However, lhapdf
   gives me 0 once I switch to MRST2004qed (10042 = lhaid).
   Any idea why?

Related branches

lp:~maddevelopers/mg5amcnlo/1.5.8
Johan Alwall (community): Approve
Olivier Mattelaer: Approve
Diff: 7090 lines (+3695/-1280)
50 files modified
Template/Cards/delphes_card_ATLAS.dat (+498/-134)
Template/Cards/delphes_card_CMS.dat (+511/-134)
Template/Cards/delphes_card_default.dat (+69/-53)
Template/Cards/delphes_trigger_ATLAS.dat (+0/-16)
Template/Cards/delphes_trigger_CMS.dat (+0/-20)
Template/Cards/delphes_trigger_default.dat (+0/-20)
Template/Source/PDF/pdf_lhapdf.f (+9/-2)
Template/Source/PDF/pdg2pdf.f (+52/-17)
Template/Source/PDF/pdg2pdf_lhapdf.f (+90/-14)
Template/SubProcesses/cuts.f (+16/-0)
Template/SubProcesses/myamp.f (+3/-1)
Template/bin/internal/run_delphes3 (+38/-0)
UpdateNotes.txt (+46/-0)
aloha/aloha_lib.py (+1/-1)
aloha/aloha_parsers.py (+5/-1)
aloha/aloha_writers.py (+1/-0)
madgraph/VERSION (+1/-1)
madgraph/core/base_objects.py (+30/-10)
madgraph/core/diagram_generation.py (+9/-3)
madgraph/core/helas_objects.py (+74/-45)
madgraph/interface/madevent_interface.py (+178/-27)
madgraph/interface/madgraph_interface.py (+23/-4)
madgraph/iolibs/export_cpp.py (+30/-8)
madgraph/iolibs/export_v4.py (+16/-6)
madgraph/iolibs/template_files/auto_dsig_v4.inc (+4/-1)
madgraph/iolibs/template_files/super_auto_dsig_group_v4.inc (+5/-0)
madgraph/various/cluster.py (+24/-17)
madgraph/various/lhe_parser.py (+246/-0)
models/EWdim6/EWdim6.log (+20/-10)
models/EWdim6/__init__.py (+23/-7)
models/EWdim6/build_restrict.py (+20/-16)
models/EWdim6/coupling_orders.py (+3/-3)
models/EWdim6/couplings.py (+46/-70)
models/EWdim6/function_library.py (+9/-1)
models/EWdim6/lorentz.py (+128/-113)
models/EWdim6/object_library.py (+22/-10)
models/EWdim6/parameters.py (+70/-170)
models/EWdim6/particles.py (+52/-52)
models/EWdim6/vertices.py (+215/-251)
models/EWdim6/write_param_card.py (+2/-2)
models/check_param_card.py (+1/-2)
models/import_ufo.py (+45/-33)
models/write_param_card.py (+2/-2)
tests/acceptance_tests/test_cmd_madevent.py (+60/-1)
tests/unit_tests/core/test_base_objects.py (+3/-1)
tests/unit_tests/core/test_helas_objects.py (+503/-0)
tests/unit_tests/iolibs/test_export_cpp.py (+283/-0)
tests/unit_tests/iolibs/test_export_v4.py (+12/-1)
tests/unit_tests/various/test_aloha.py (+63/-0)
tests/unit_tests/various/test_lhe_parser.py (+134/-0)
Revision history for this message
Johan Alwall (johan-alwall) wrote :

Dear Marc-Andre,

We are using the LHAPDF function evolvePDF to evaluate PDFs in the LHAPDF framework. As you can see from the LHAPDF manual at https://lhapdf.hepforge.org/manual, there is no photon PDF included in this call; f(-6:6) in the call only has entries for the 6 quark flavors and the gluon. The MRST2004qed PDF set has a special function, evolvePDFphoton, to get the photon PDF. If you need to use this, please feel free to implement it in the Source/PDF/pdg2pdf_lhapdf.f and Source/PDF/pdf_lhapdf.f files. It is at this point too much of a special case for us to make a general implementation including this at this point, but if many people need it, we might change our mind.

All the best,
Johan

Changed in madgraph5:
status: New → Opinion
importance: Undecided → Wishlist
Revision history for this message
Olivier Mattelaer (olivier-mattelaer) wrote :

Hi Johan,

I would like to have this implemented. I'm going to implement this for version 1.5.8

Cheers,

Olivier

PS: Thanks for the hint concerning the problem.

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) wrote :

Ok I've push a fix for this in 1.5.8.

Johan, could you take a look at the mofidifcation?

Cheers,

Olivier

Changed in madgraph5:
status: Opinion → Fix Committed
assignee: nobody → Olivier Mattelaer (olivier-mattelaer)
Olivier Mattelaer (olivier-mattelaer)
Changed in madgraph5:
status: Fix Committed → Fix Released
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