Number of event in delphes root files after matching

[olivier]

Question From Danielle Barduci:
​https://answers.launchpad.net/madgraph5/+question/241025

Hi,
I am generating 10k events for the following process
generate p p > e- ve~ @1
add process p p > e- ve~ j @2
with matching procedure performed with pythia and going also at delphes level.

After pythia I correctly have a certain number of rejected events (9780 remaining events after matching).
However in the root file generate by delphes I still have 10k events and if I try to make plots from the root file these looks slightly different from the one provided by MadGraph. Why delphes doesn't have the 9780 events but the initial 10k?

Moreover under the plots at Delphes level provided by MG there is written the parton level cross section instead that the matched cross section, and I can't understand why.

Thanks in advance for the help,

Daniele

[Michele Selvaggi]

Hi Daniele,

sorry for the late answer.
I suspect you are still using an old madgraph version with Delphes2.
Can you try using Delphes3?

You can use you *.hep file (output from madgraph+pythia) as input for Delphes3.

You can run Delphes standalone in the following way:

./DelphesSTDHEP examples/delphes_card_CMS.tcl delphes_output.root input.hep

You can find all instructions on Delphes 3 here:

https://cp3.irmp.ucl.ac.be/projects/delphes

Cheers,
Michele