Particles and Constituents in Jets

[teddy]

Dear Delphes Authors:

If I want to get information of the particles inside the jets, how should I do? What exactly are in the Particles and Constituents in the Jets Class? Should I use Particles or Constituents?

Further, I find in Example3.C how to get constituents in Jets. It seems there are three kind of things inside the constituents: Tower, Track, GenParticle. What exactly are these three things? According to my own understanding, the Track stores each charged particle and the Tower stores the neutral ones within each Calorimeter Tower. But when I check some root files, I find that inside Tower, it contains some charged particles which does not appear in Track. And there is nothing in the GenParticle category.

And, also I use similar method to get particles in Jets. I find that in the TRefArray of the Particles inside the Jets, there are some particles appear twice or even more. How is this happen?

Thanks very much!

Best!

Ted

[Michele Selvaggi]

Hi Ted,

sorry for the late answer.
As you say, Example3.C is what you should look at to access jet constituents, and the relevant array is Constituents (please ignore Particles).

For reconstructed jets (i.e. Jet in the default cards), you should find only constituents of type Tower or Track (since by default the particle-flow algorithm is used there should be no double counting), whereas for generated jets (GenJet) you should find only GenParticles.

Michele