A bug on b-tagging in CMS Delphes card

[Sung Hak Lim]

Dear Delphes team,

I recently found a bug on b-tagging in CMS Delphes card.

In a recent version of Delphes.3.3.0, b-tagging parameterisations to recent ATLAS and CMS publications is updated.

At b-tagging module on delphes_card_CMS.tcl says:

=============================

###########
# b-tagging
###########

module BTagging BTagging {

set JetInputArray JetEnergyScale/jets

set BitNumber 0

# add EfficiencyFormula {abs(PDG code)} {efficiency formula as a function of eta and pt}
# PDG code = the highest PDG code of a quark or gluon inside DeltaR cone around jet axis
# gluon's PDG code has the lowest priority

# based on ​arXiv:1211.4462

# default efficiency formula (misidentification rate)
add EfficiencyFormula {0} {0.01+0.00038*pt}

# efficiency formula for c-jets (misidentification rate)
add EfficiencyFormula {4} {0.25*tanh(0.018*pt)*(1/(1+ 0.0013*pt))}

# efficiency formula for b-jets
add EfficiencyFormula {5} {0.85*tanh(0.0025*pt)*(25.0/(1+0.063*pt))}

}

=============================

I compared these efficiency formula with results of CSVM tagger on ​arXiv:1211.4462.

b-tagging efficiency and c-jet misidentification rate fit the result well. However, light jet misidentification rate is overestimated and it even reaches ~30% at jet PT ~ 500 GeV

If I use a formula 0.01+0.000038*pt , it seems the equation fits the result well.

Is this a bug?

Best wishes,
Sung Hak Lim

[Sung Hak Lim]

CMS b-jet tagging efficiency on Delphes card overlaied with CSVM tagger result on ​arXiv:1211.4462

[Sung Hak Lim]

Modified CMS b-jet tagging efficiency on Delphes card overlaied with CSVM tagger result on ​​arXiv:1211.4462

[Michele Selvaggi]

Dear Sung,

it seems you are correct, thanks a lot for spotting this.
It has now been corrected in the repository version.
We'll make a new release very soon.

Thanks,
Michele

[Sung Hak Lim]

Dear Michele,

Thanks for fast reply. I saw the repository is updated.

Okay, then I'll use the repository version until new release appears.

I'm looking forward to see a next release!

Best wishes,
Sung

Replying to mselvaggi:

Dear Sung,

it seems you are correct, thanks a lot for spotting this.
It has now been corrected in the repository version.
We'll make a new release very soon.

Thanks,
Michele

[Michele Selvaggi]

Version 3.3.1 was just released.