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Event Generators for High-Energy Physics Experiments

by J. M. Campbell, M. Diefenthaler, T. J. Hobbs, S. Höche, J. Isaacson, F. Kling, S. Mrenna, J. Reuter, S. Alioli, J. R. Andersen, C. Andreopoulos, A. M. Ankowski, E. C. Aschenauer, A. Ashkenazi, M. D. Baker, J. L. Barrow, M. van Beekveld, G. Bewick, S. Bhattacharya, C. Bierlich, E. Bothmann, P. Bredt, A. Broggio, A. Buckley, A. Butter, J. M. Butterworth, E. P. Byrne, C. M. Carloni Calame, S. Chakraborty, X. Chen, M. Chiesa, J. T. Childers, J. Cruz-Martinez, J. Currie, N. Darvishi, M. Dasgupta, A. Denner, F. A. Dreyer, S. Dytman, B. K. El-Menoufi, T. Engel, S. Ferrario Ravasio, D. Figueroa, L. Flower, J. R. Forshaw, R. Frederix, A. Friedland, S. Frixione, H. Gallagher, K. Gallmeister, S. Gardiner, R. Gauld, J. Gaunt, A. Gavardi, T. Gehrmann, A. Gehrmann-De Ridder, L. Gellersen, W. Giele, S. Gieseke, F. Giuli, E. W. N. Glover, M. Grazzini, A. Grohsjean, C. Gütschow, K. Hamilton, T. Han, R. Hatcher, G. Heinrich, I. Helenius, O. Hen, V. Hirschi, M. Höfer, J. Holguin, A. Huss, P. Ilten, S. Jadach, A. Jentsch, S. P. Jones, W. Ju, S. Kallweit, A. Karlberg, T. Katori, M. Kerner, W. Kilian, M. M. Kirchgaeßer, S. Klein, M. Knobbe, C. Krause, F. Krauss, J. Lang, J. -N. Lang, G. Lee, S. W. Li, M. A. Lim, J. M. Lindert, D. Lombardi, L. Lönnblad, M. Löschner, N. Lurkin, Y. Ma, P. Machado, V. Magerya, A. Maier, I. Majer, F. Maltoni, M. Marcoli, G. Marinelli, M. R. Masouminia, P. Mastrolia, O. Mattelaer, J. Mazzitelli, J. McFayden, R. Medves, P. Meinzinger, J. Mo, P. F. Monni, G. Montagna, T. Morgan, U. Mosel, B. Nachman, P. Nadolsky, R. Nagar, Z. Nagy, D. Napoletano, P. Nason, T. Neumann, L. J. Nevay, O. Nicrosini, J. Niehues, K. Niewczas, T. Ohl, G. Ossola, V. Pandey, A. Papadopoulou, A. Papaefstathiou, G. Paz, M. Pellen, G. Pelliccioli, T. Peraro, F. Piccinini, L. Pickering, J. Pires, W. Placzek, S. Plätzer, T. Plehn, S. Pozzorini, S. Prestel, C. T. Preuss, A. C. Price, S. Quackenbush, E. Re, D. Reichelt, L. Reina, C. Reuschle, P. Richardson, M. Rocco, N. Rocco, M. Roda, A. Rodriguez Garcia, S. Roiser, J. Rojo, L. Rottoli, G. P. Salam, M. Schönherr, S. Schuchmann, S. Schumann, R. Schürmann, L. Scyboz, M. H. Seymour, F. Siegert, A. Signer, G. Singh Chahal, A. Siódmok, T. Sjöstrand, P. Skands, J. M. Smillie, J. T. Sobczyk, D. Soldin, D. E. Soper, A. Soto-Ontoso, G. Soyez, G. Stagnitto, J. Tena-Vidal, O. Tomalak, F. Tramontano, S. Trojanowski, Z. Tu, S. Uccirati, T. Ullrich, Y. Ulrich, M. Utheim, A. Valassi, A. Verbytskyi, R. Verheyen, M. Wagman, D. Walker, B. R. Webber, L. Weinstein, O. White, J. Whitehead, M. Wiesemann, C. Wilkinson, C. Williams, R. Winterhalder, C. Wret, K. Xie, T-Z. Yang, E. Yazgan, G. Zanderighi, S. Zanoli, K. Zapp

Submission summary

Authors (as registered SciPost users): Christian Bierlich · Enrico Bothmann · Andy Buckley · Jonathan Butterworth · Smita Chakraborty · Tim Engel · Stefan Höche · Joshua Isaacson · Alexander Karlberg · Max Knobbe · Claudius Krause · Stephen Mrenna · Mathieu Pellen · Tilman Plehn · Daniel Reichelt · Gavin Salam · Steffen Schumann · Ludovic Scyboz · Frank Siegert · Jennifer Smillie · Yannick Ulrich · Ramon Winterhalder · Melissa van Beekveld
Submission information
Preprint Link: scipost_202311_00035v1  (pdf)
Date accepted: 2024-03-12
Date submitted: 2023-11-20 21:43
Submitted by: Höche, Stefan
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Phenomenology
Approach: Phenomenological


We provide an overview of the status of Monte-Carlo event generators for high-energy particle physics. Guided by the experimental needs and requirements, we highlight areas of active development, and opportunities for future improvements. Particular emphasis is given to physics models and algorithms that are employed across a variety of experiments. These common themes in event generator development lead to a more comprehensive understanding of physics at the highest energies and intensities, and allow models to be tested against a wealth of data that have been accumulated over the past decades. A cohesive approach to event generator development will allow these models to be further improved and systematic uncertainties to be reduced, directly contributing to future experimental success. Event generators are part of a much larger ecosystem of computational tools. They typically involve a number of unknown model parameters that must be tuned to experimental data, while maintaining the integrity of the underlying physics models. Making both these data, and the analyses with which they have been obtained accessible to future users is an essential aspect of open science and data preservation. It ensures the consistency of physics models across a variety of experiments.

List of changes

We thank the referees for their constructive reports. In order to address the specific concerns, we have made the following changes to the manuscript:

Report 1:
- We have added subsection 8.4.6 to give an overview of the physics capabilities of PHOTOS.
- We have also included dedicated sections on BabaYaga (8.4.4) and BHLumi/BHWide (8.4.5).
- We have mentioned both Horace and BabaYaga in section 2.3.1 on QED showers.

Report 2:
- We have added definitions of acronyms at their first occurrence in the text.
- We have added a description of expected LHCb measurements to Section 1.1.
- We have included a description of the work in JHEP 11 (2019) 061 to Sec. 2.2.3.
- We have added comments on the deficiencies of hadronization models and possible future directions of development in Sec. 2.4.1 and 2.4.3.
- We have rephrased the ambiguous sentence in Sec. 3. It now reads: "While many aspects of event generators are based on first principle calculations, event generators also allow to interface these calculations with phenomenological models, which necessarily include tune-able parameters.”
- We have made the statement on LO PDFs on page 24 (now page 27) more explicit.
- We have included the referee’s comment on Sec. 3.4 in the main text (page 32).
- We have added references on parallelization, vectorization and the use of accelerators to the main text and commented on the status of developments in Sec. 3.4 (page 33).
- We added a few sentences that generative networks require existing MC events, and that they do not provide any new understanding of the underlying physics (page 34).
- A short subsection, mostly containing references to the original work on the STRIPPER code, has been added to Section 4.1.
- The mistake in Section 4.1.5, page 42 (now page 44) has been corrected.
- We have commented on the status of matching and merging of QCD and QED emissions in Sec. 4.3.2.
- We have corrected the sentence on POWHEG in Sec. 4.3.1 and added the missing reference to Whizard.
- We have restructured the paragraph on negative weights in POWHEG in Sec. 4.7.3 and commented on the fact that POWHEG is not always the preferred option to eliminate negative weights.
- We have improved the sentence on parton shower variations in Sec. 4.7.4 by referring explicitly to the renormalization and factorization scales.

Current status:
Accepted in target Journal

Editorial decision: For Journal SciPost Physics: Publish
(status: Editorial decision fixed and (if required) accepted by authors)

Reports on this Submission

Anonymous Report 2 on 2024-1-23 (Invited Report)


This paper presents a comprehensive overview of the status of the state of the art Monte-Carlo event generators for high-energy particle physics.

The text level is appropriate and well-balanced, with sufficient pedagogical introductory information for the paper to be useful for newcomers in the field and with enough detail to be valuable reference for experts.

I recommend publication of the paper.

  • validity: top
  • significance: top
  • originality: -
  • clarity: high
  • formatting: perfect
  • grammar: excellent

Anonymous Report 1 on 2023-12-19 (Invited Report)


I am happy with the authors clarifications and with the modifications included in the revised manuscript.
I have no hesitation to recommend this manuscript for publication.

  • validity: -
  • significance: -
  • originality: -
  • clarity: -
  • formatting: -
  • grammar: -

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