Insalling Delphes3

[Guglielmo Coloretti]

Dear all,

I am using Delphes3 interfaced with Pythia8. Whenever I am trying to run the script DelphesHepMC3 on some hepmc file obtained with Pythia8, I get the following error:

ERROR: invalid vertex format-------------------------------------] (0.00%)

I installed Delphes both via MadGraph5aMCatNLO and manually, but I still get the same error.

DelphesHepMC and DelphesHepMC2 are working fine instead.

Best regards,
Guglielmo Coloretti

[Pavel Demin]

DelphesHepMC2 can read HepMC2 format. DelphesHepMC3 can read HepMC3 format.

If DelphesHepMC2 can read the file and DelphesHepMC3 cannot read the file, then it means that the file format is HepMC2 and you should use DelphesHepMC2 to read this file.

[Guglielmo Coloretti]

Dear Pavel,

Thank you very much for your reply. I was wondering if you know why Pythia8 is producing hepmc2 file instead of hepmc3 ones, which are the latest.

Best regards,
Guglielmo Coloretti

[Pavel Demin]

According to the Pythia documentation at

​https://pythia.org/latest-manual/HepMCInterface.html

different Pythia classes (Pythia8ToHepMC and Pythia8ToHepMC3) are used to write different formats.

If the Pythia code that you are using generates HepMC2 files, then it means that this code is using Pythia8ToHepMC and not Pythia8ToHepMC3.

[Guglielmo Coloretti]

Dear Pavel,

I completely understand now. Thank you very much!

Best regards,
Guglielmo