What is the convention of the status code?

[liuda]

Hi,

I am converting the hep.gz output by pythia6.4 to root files by using the command:

./DelphesSTDHEP examples/converter_card.tcl

I am asking that what is convention of the particle status in the Genparticle class? Is it same with the HepMC convention?

Actually, I am doing the b-tagging by comparing the momenta of the b-parton to the jets reconstructed by fast jet, I should select the b-partons as status = 2, right?

These b-partons correspond to the final partons after PS, before fragmentation. Am I right?

What is the way of b-tagging in Delphes?

Thanks in advance

Best wishes,

Da

[Michele Selvaggi]

Hi,

if you are using hep format created by MadGraph/Pythia6, then you should have as
status
3: hard scattering
2: unstable
1: stable

Concerning the btagging question, yes, looking at status 2 partons seems fine.
In Delphes for btagging we look for any (meaning status 2 or 3) b parton matching the jet.

Michele

[liuda]

Hi,

Thanks a lot. but what is about the case that a parton has emitted another parton? For example, b1 -> b2 + g, then b2 hadronized. Is b1 still kept? If so, what is its status?

Best wishes,
Da

Replying to mselvaggi:

Hi,

if you are using hep format created by MadGraph/Pythia6, then you should have as
status
3: hard scattering
2: unstable
1: stable

Concerning the btagging question, yes, looking at status 2 partons seems fine.
In Delphes for btagging we look for any (meaning status 2 or 3) b parton matching the jet.

Michele

[Michele Selvaggi]

I believe in the case you describe b2 will be status 2, same as b1. It will just appear earlier in the decay chain.
I guess you can check that by printing the mothers and daughters (by accessing M1(2), D1(2) from GenParticle class).

Michele

[liuda]

Hi,

Thank you very much. It is very helpful to me.

Best wishes,

Da Liu

Replying to mselvaggi:

I believe in the case you describe b2 will be status 2, same as b1. It will just appear earlier in the decay chain.
I guess you can check that by printing the mothers and daughters (by accessing M1(2), D1(2) from GenParticle class).

Michele

[liuda]

Replying to liuda:

Hi,

Thanks a lot. but what is about the case that a parton has emitted another parton? For example, b1 -> b2 + g, then b2 hadronized. Is b1 still kept? If so, what is its status?

Best wishes,
Da

Replying to mselvaggi:

Hi,

if you are using hep format created by MadGraph/Pythia6, then you should have as
status
3: hard scattering
2: unstable
1: stable

Concerning the btagging question, yes, looking at status 2 partons seems fine.
In Delphes for btagging we look for any (meaning status 2 or 3) b parton matching the jet.

Michele

Hi,

I have seen that in the examples/delphes_card_ATLAS.tcl files, for the btagging part,

you have the command:

set PartonPTMin 1.0

I guess this cut is for the pT of the comparing b-partons. Why is this value so small? What is the motivation to choose 1.0?

Thanks in advance.

Best wishes,
Da

[Pavel Demin]

Just for information.

The following wiki page contains links to some web pages describing the status codes produced by Pythia and Herwig:

https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/Candidate

[Pavel Demin]

Concerning PartonPTMin in the b-taggin module. There is now particular reason for it to be so low. We tried to set it to 10 and didn't observe any changes.