Skip to content

Conversation

@vasilllis
Copy link
Contributor

@BrieucF @kjvbrt Can you please check EvtGen + Pythia tutorial. I have refined all comments from Hands-On tutorial.

@kjvbrt
Copy link
Contributor

kjvbrt commented Nov 20, 2025

Can you add author: Your name tag at the beginning of the section?

- Use this setup if you want to run the latest compatible versions of the FCC software:

**Event generation**
To generate events with Pythia8 + EvtGen, use the executable ```DelphesPythia8EvtGen_EDM4HEP_k4Interface```. Make sure your FCC software setup is actually working in correct enviroment. You can check this by running:
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Why multiple backticks? One should be enough for an in-line term

To generate events with Pythia8 + EvtGen, use the executable ```DelphesPythia8EvtGen_EDM4HEP_k4Interface```. Make sure your FCC software setup is actually working in correct enviroment. You can check this by running:
```bash
source /cvmfs/fcc.cern.ch/sw/latest/setup.sh
which DelphesPythia8EvtGen_EDM4HEP_k4Interface
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

What is the expected output? How do I know that the executable is from the correct stack?

The executable wrapper that connects Pythia8, EvtGen, and Delphes, and writes output in EDM4hep format. You can inspect its expected argument order by running:
```bash
echo $KEY4HEP_STACK
DelphesPythia8EvtGen_EDM4HEP_k4Interface -h
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can you add closed admonition with the output?

Here we download a custom EvtGen decay file `Bu2TauNuTAUHADNU.dec` to describe $B^{+} \;\rightarrow\; \tau^{+} \nu_{\tau} \;\rightarrow\; 3\pi$.
EvtGen uses a flexible text-based format to define particle decays, allowing users to override or extend the default decay tables. To do this safely — without altering the global definitions in `DECAY.DEC` — we use **aliases**, which act as local copies of particles.

Example `.dec` file:
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Here Iit might be beneficial to have an admonition as well.

**EvtGen** is a decay generator specialized in the simulation of hadronic decays of heavy-flavour particles with accurate angular correlations and form-factor models.
**EvtGen** is interfaced to [**Pythia8**](https://github.com/HEP-FCC/k4Gen/blob/main/k4Gen/src/components/PythiaInterface.h#L88-L97) through **k4Gen**,
so that events generated by **Pythia** can be decayed by **EvtGen** before detector simulation.
**EvtGen** is a decay generator specialized in the simulation of hadronic decays of heavy-flavour particles with accurate angular correlations and form-factor models. **EvtGen** is interfaced to [**Pythia8**](https://github.com/HEP-FCC/k4Gen/blob/main/k4Gen/src/components/PythiaInterface.h#L88-L97) through **k4Gen**, so that events generated by **Pythia** can be decayed by **EvtGen** before detector simulation.
Copy link
Contributor

@kjvbrt kjvbrt Nov 20, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If there is a website for EvtGen, can it be linked?

@kjvbrt kjvbrt merged commit 335bc44 into HEP-FCC:main Nov 26, 2025
2 checks passed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants