Question on angular bias/resolution

[Ernesto Arganda]

Dear authors,

Since we are attempting to perform an analysis that seems to have a very high sensitivity to angular bias and resolution, we will need to achieve the most realistic possible implementation that accounts for them.

In particular, we'd like to ask you whether jet angular bias/resolution distributions like those shown in Figs. 5.6 and 5.7 in ​http://cds.cern.ch/record/1441943/files/FengEric_Thesis.pdf are reached for the ATLAS simulation in Delphes?

We couldn't find any detailed discussion on this matter in the Delphes 3.0 paper.

Thanks for your help,

Ernesto Arganda, Ezequiel Álvarez, Alejandro Szynkman.

[Michele Selvaggi]

Hello,

really sorry for the late reply.
I unfortunately cannot answer this question since we have never tried to produce the plots you mention.
I suggest you try yourself to produce them by matching reco jets (Jet collection) with mc jets (GenJet collection).

I would be surprised if you get the correct angular resolution without tuning.
What you can do is to tune the calorimeter granularity in the delphes_card so to reproduce your needed resolution.

The granularity in the card is defined around line 200 in https://cp3.irmp.ucl.ac.be/projects/delphes/browser/trunk/examples/delphes_card_ATLAS.tcl.

Let us know if you need help with this.

Michele

[toodles]

Dear authors,

I also need to change the granularity of delphes. I looked into the delphes_card, but cannot find this

parameter actually. How can I define or modify the granularity of delphes?

Thanks for your help

Regards,
Ying-Ying

[Michele Selvaggi]

Hi Ying-Ying,

you can actually modify the calorimeter granularity in the appropriate section of the card.
For instance, from line 230-260 in the CMS card: ​https://github.com/delphes/delphes/blob/master/cards/delphes_card_CMS.tcl

The syntax should be pretty self explanatory, but to help you out see another example with very fine granularity:

  # 1 degree towers
  set PhiBins {}
  for {set i -72} {$i <= 72} {incr i} {
    add PhiBins [expr {$i * $pi/72.0}]
  }

  # 0.01 unit in eta up to eta = 3
  for {set i -60} {$i <= 60} {incr i} {
    set eta [expr {$i * 0.05}]
    add EtaPhiBins $eta $PhiBins
  }

Hope this helps,
Cheers,
Michele