Using Fastjet in Pythia to plot distribution of particles

In summary, the quickstart example provides an example of how to access the jet constituents. You can access the fastest particle out of the particles which have formed the jet by using the functions shown in the quickstart example.
  • #1
Sandeep Hundal
9
0
I am using fastjet in pythia8.I am studying jet formation in pp collisions.I need to plot distribution of transverse momentum of fastest particle in fastest jet formed in 1000 events simulated.But i don't know how to access particle properties after jet formation.Like if I want to know the fastest particle out of the particles which have formed that jet ,I am not able to access it.Can anybdy explain ?
Thanks
 
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  • #2
The fastest particle? That is an unusual quantity.

The quickstart has an example how to access the jet constituents.
 
  • #3
by fastest you mean the one with the highest pt? (would make more sense at least from my experience)
 
  • #4
yes ,here fastest means with highest pt
 
  • #5
mfb said:
The fastest particle? That is an unusual quantity.

The quickstart has an example how to access the jet constituents.
It worked
Thanks
 
  • #6
How can we access lowest pt particle(constituent) of sub leading jet ?
 
  • #7
Does Section 3.5 of the manual not cover that?
 
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Likes ChrisVer
  • #8
The functions shown in the quickstart example are sufficient for this as well.
 
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Likes Sandeep Hundal
  • #9
yes,It worked now.Actually in some of the events,only less than 2 jets were formed.so It gave an error.Now I have imposed the condition to select only those events that have more than 1 jet.Now the question is -is that possible that in some events no jet formed even after clustering in pythia using fastjet?
Thanks .Your guidance is helping me a lot :)
 
  • #10
It depends on the events simulated, but in general: sure. Not every pp collision produces particles high-energetic enough to be included in jets. Some don't produce particles in the detector at all.
 
  • #11
Sandeep Hundal said:
Now the question is -is that possible that in some events no jet formed even after clustering in pythia using fastjet?
Hmmm, I would like to know what you define as a jet? Would a muon give you a jet?
As jets I was imagining objects of grouped clusters (which are grouped cells), that satisfy certain quality criteria (some energy thresholds and so on). Those are formed only for signals recorded in the calorimeter (so objects that are recoed from the calorimeter won't be called jets?).
Then are you referring to the jets that come from the hard scattering process?
 
  • #12
yes,I am referring to the jets that come from hard scattering processes after fragmentation and hadronization.
 
  • #13
So ignoring the pileup jets, the process: [itex] qq\to W \to \mu \nu[/itex] wouldn't necessarily give you a "jet" in your event.
 

1. How do I use Fastjet in Pythia to plot the distribution of particles?

To use Fastjet in Pythia for plotting particle distributions, you first need to install the Fastjet library and link it to Pythia. Then, you can define the jet algorithm and parameters, run the event generation with Pythia, and use Fastjet to cluster the final state particles into jets. Finally, you can plot the jet properties and particle distributions using a suitable software, such as ROOT.

2. What is the purpose of using Fastjet in Pythia for particle distribution analysis?

Fastjet in Pythia allows for a more accurate and efficient analysis of particle distributions by using advanced jet algorithms and providing various tools for jet reconstruction and visualization. This combination enables researchers to study the underlying physics processes in more detail and extract valuable information about the particles' properties and interactions.

3. Can Fastjet in Pythia be used for different types of collisions and energies?

Yes, Fastjet in Pythia is a versatile tool that can be used for a wide range of collision types and energies, including proton-proton collisions at the LHC and electron-positron collisions at the ILC. It also supports different jet algorithms and parameters, making it suitable for various research purposes.

4. What are some common challenges when using Fastjet in Pythia for particle distribution analysis?

Some common challenges when using Fastjet in Pythia include selecting the appropriate jet algorithm and parameters for a specific analysis, understanding and interpreting the jet properties and distributions, and dealing with potential background or pile-up effects. It is crucial to carefully choose the input parameters and perform thorough background studies to ensure accurate results.

5. Are there any resources available for learning how to use Fastjet in Pythia for particle distribution analysis?

Yes, there are various resources available, such as user manuals, tutorials, and online forums, that provide guidance and support for using Fastjet in Pythia. Additionally, many research groups and collaborations use Fastjet in Pythia for their analyses, so it is beneficial to consult with experienced researchers for tips and advice.

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