Jet constituents

1

Hello everyone,

I want to get the reconstructed particles that were used to cluster a certain jet. The jet clustering algorithm I use is Durham kt algorithm. There is the JetClusteringUtils.cc and JetConstituentsUtils.cc that both have get_constituents() functions. But I don’t know which ones I should use.

Best regards
Yehia

2

Hi @ymahmoud,

what is the analyzer you are using for the clustering?

I found this example:

df = df.Define("clustered_jets", "JetClustering::clustering_ee_kt(2, 2, 0, 10)(pseudo_jets)") # 2-jet e
xclusive clustering
                                                                                                           
    df = df.Define("jets", "FCCAnalyses::JetClusteringUtils::get_pseudoJets(clustered_jets)")
    df = df.Define("jetconstituents", "FCCAnalyses::JetClusteringUtils::get_constituents(clustered_jets)")

examples/FCCee/higgs/jetclustering/histmaker.py

Best,
Juraj

3

Hi @jsmiesko

I used a similar analyzer to the one you quoted. The thing is I don’t understand what type of objects does FCCAnalyses::JetClusteringUtils::get_constituents() returns. I would expect it to return a vector of Reconstructed particles for each jet but instead it returns a vector of integers
as in:

What does the integer reference here?

4

Hi @ymahmoud

The integers represent the index of the particle in the input collection (see comment in the example). So in the example, the clustering is done on a collection of reco particles without the muons rps_no_muons, so the integers represent (for each jet), the the position of each particle of that jet in the rps_no_muons.

Best,
Jan

1 Like
5

Thank you @jaeyserm !