Dear Delphes authors,

I am generating samples using Madgraph+Phythia+Delphes and I am using the delphes cards that come with the Delphes instalation.

When I used the "delphes_card_ATLAS_PileUp.tcl", I have a strange peak of events for photons with eta = -2 and E ~= 40 GeV.

If I use the "delphes_card_ATLAS.tcl" instead (without PileUp) the problem is not present.

This problem is common in diferent decays and it is more noticible for samples that don't have a photon in the main decay, for example: "generate p p > t t~ > w+ w- b b~ , (w+ > vl l+) , (w- > j j )" .
(I have the plots for this sample bellow, for generations with 5k events)

I can't find a reason for this peak, it only happens for the photons.

I am using the following versions:
Madgraph-3.3.1
Delphes-3.5.0

Thank you in advance!