LHC Monte Carlo WG subgroup meeting – data sharing and new workflows

Thursday 2 Oct 2025, 13:00 → 17:00 Europe/Zurich

CERN

13:00 → 13:10 Introduction

Speaker: Enrico Bothmann (CERN)

13:10 → 14:05 Parton-level event samples

contributors:
- Sherpa/Pepper (Enrico Bothmann/Chris Gütschow)
- MadGraph (Olivier Mattelaer et al.)
- other generators?
- experiments?

discussion points:
- Shared starting point for further merging/matching, shower, hadronisation, …
- No model parameters; PDF, scales, … etc. can be easily reweighted.
- Open Data → pheno projects, source to fill interpolation grids, …
- Workflow aspect: Large PL samples can be generated on HPC/GPU and then served to WLCG nodes for further processing (how?); factorising parton-level production allows for fast shower/hadronisation comparisons
- Preference format for storage/usage: stick with plain LHE? H5? Others?

Speaker: Enrico Bothmann (CERN)

14:05 → 15:00 Particle-level event samples

contributors:
- generators?
- experiments?

discussion points
- What is the status of such efforts?
- Can we do more/better?
- Are there technical stumbling blocks?
- Is there something to be done on the generators’ side to facilitate this?

15:00 → 15:30 Break

15:30 → 16:15 Storage and distribution of Monte Carlo event samples

contributors:
- experiments?
- Rucio?
- Zenodo?

discussion points:
- Overview and new developments
- Will we run into storage problems with MC samples?
- If so, to what degree can event sharing be a remedy?
- Is there any issue to be aware of with loading input files (via Rucio?) to WLCG nodes for further processing? (this might also be discussed in the parton-level discussion)

16:15 → 17:00 Open Data for Monte Carlo event samples

contributors:
- CERN Open Data projects?
- Experiments?

discussion points
- Overview and new developments
- What is the experience so far, what is the uptake?
- How can we ensure to maximise the usefulness?