Forum on the Interpretation of the LHC Results for BSM studies

The quest for new physics beyond the Standard Model is arguably the driving topic for Run 2 of the LHC. Indeed, the LHC collaborations are pursuing searches for new physics in a vast variety of channels. While the collaborations typically provide themselves interpretations of their results, for instance in terms of simplified models, the full understanding of the implications of these searches requires the interpretation of the experimental results in the context of all kinds of theoretical models. This is a very active field, with close theory-experiment interaction and with several public tools being developed.

With this forum, we want to provide a platform for continued discussion of topics related to the BSM (re)interpretation of LHC data, including the development of the necessary public RecastingTools and related infrastructure.

If you have questions or want to contribute, contact Sabine Kraml,, or any of the topical contacts given below.


Meetings of this forum

Other workshops, potentially interesting for our forum

Mailing list

Steering group

The steering group comprises a representative of each of the public recasting tools as well as a couple of individual LHC physicists. Current members are:

Jon Butterworth, Andy Buckley, Kyle Cranmer, Matthias Danninger, Nishita Desai, Matthew Dolan, Benjamin Fuks, Marie-Helene Genest, Ahmed Ismail, Sabine Kraml, Frank Krauss, Michael Krämer, Nazila Mahmoudi, Michelangelo Mangano, Stefano Moretti, Pat Scott, Sezen Sekmen, Wolfgang Waltenberger, Nick Wardle, Andreas Weiler.

Mailing list: :

Many thanks to previous members: Suchita Kulkarni, Jamie Tattersall


[2020-10-22] The (virtual) LLP Workshop 16-19 Nov will have a hands-on Reinterpretations WG session on Wednesday Nov 18th between 13:00-15:00 CERN time.

[2020-08-21] Our Forum's report Reinterpretation of LHC Results for New Physics: Status and recommendations after Run 2 has been published in SciPost Phys. 9, 022 (2020)

[2019-10-25] The Les Houches Recommendations 3(b) and 3(c) have been achieved for the first time as of this week. In ATL-PHYS-PUB-2019-029, ATLAS described the "statistical reproduction" of the SUSY sbottom multi-b analysis using a plain-text serialization of the likelihood. As of this week, the plain-text serialization has been made available on HEPdata (click "Resources" -> "Common Resources"). See also the CERN seminar by Lukas Heinrich in this context.

[2018-12-19] Created a Zenodo community on (Re)interpretation of LHC results for BSM studies; it is ready to receive your recast data and codes, basically "Everything that has to do with the (re)interpretation of LHC results for beyond-the-Standard Model (BSM) physics".

[2018-08-15] Version 1.2 of SModelS supports long-lived particle (HSCP and R-hadron) signatures, covariance matrices for the combination of signal regions, and can produce interactive plots. Detailed list of what's new.

[2018-08-01] arXiv:1808.00480: a very complete (100+ pages!) review of "Confronting new physics theories to LHC data with MadAnalysis 5" by E. Conte and B. Fuks.

[2018-04-06] Matthias Danninger (ATLAS) and Nick Wardle (CMS) join the steering group.


Topics, ongoing and proposed efforts

  • Review of tools for the BSM (re)interpretation of LHC data : see RecastingTools

  • Implications of SM (incl. top and Higgs) measurements: See talks by Florian Bernlochner on Higgs fiducial cross sections and Jon Butterworth on using SM measurements at the kick-off meeting as well as ATLAS & CMS reviews of Standard Model/top measurements and re-use for constraining BSM at 2nd workshop (Monday afternoon). Useful: publish SM theory predictions in HepData.
    • Contacts: Jon Butterworth

  • Digitized information: Lots of useful 'data' still has to be read off from tiny paper plots (and/or is difficult to be found at all) --> Encourage as much as possible the systematic use of the new HEPData; this concerns the publication of results but also auxiliary material and -very important- performance plots. HEPData itself makes an effort to become better searchable and more user-friendly.
    • Contacts: Frank Krauss, Graeme Watt
    • see also: PhenoData database

  • Validation material: continue and improve interaction with experimental groups on providing (auxiliary) material necessary for a rigorous validation of recast codes: well defined benchmark points, detailed MC settings (run cards!), detailed cutflows for preselection and all signal regions. NEW: A discussion / Q&A forum should be set up to give feedback on the quality of the documentation and show how well different results can be used and how much they are being used. We should review the importance of various elements, to help the time-constrained experimental analysis teams prioritise. See final discussion of the Dec 12-14, 2016 workshop.

  • Correlation matrices: an example of an experiment producing a correlation matrix for systematics between bins in a single analysis, and a corresponding pheno recast making use of it in a likelihood function. Some work has started on this in GAMBIT together with people from CMS. It will be useful to have example recasts showing the usefulness of this extra info. Could an extensible approach with decomposition into correlated and fully correlated errors from identified standard error sources be agreed?

  • Interpretation of resonance searches: depending on the signal assumptions, using directly the cross section ⨉ branching ratio limits from the experimental paper can be quite misleading. So far, we have no dedicated discussion of this in our Forum. See e.g. arXiv:1801.08129 for a recent relevant paper ....

  • BSM analysis implemented in Rivet: as from v2.5.0 efficiencies and smearing can be used in Rivet to deal with results which are not unfolded (the typical BSM case). Efficiencies are particularly relevant for leptonic analyses and/or analyses involving b-jets. The Rivet implementation allows the efficiency and smearing functions to be completely specific to each analysis. Some LHC Run 2 analyses are implemented already but need further validation and comparison to recast tools using Delphes3.
    • Contacts: Andy Buckley

  • Multi-variant or BDT analyses: how to publish the MVA or BDT `function' for use in public tools? Try to come up with a working example; again to be done in collaboration with a sympathetic analysis group from ATLAS or CMS (best both).

  • Publishing full likelihoods: Publication of full likelihoods of LHC experiment analyses to HEPData using a plain-text serialization. See "Reproducing searches for new physics with the ATLAS experiment through publication of full statistical likelihoods" (ATL-PHYS-PUB-2019-029) and the HEPData entry for the corresponding ATLAS SUSY analysis as an example, which uses the JSON schema developed by pyhf for HistFactory models.
    • Contact: Giordon Stark (ATLAS), Lukas Heinrich (ATLAS), Matthew Feickert (ATLAS)

  • Usability of SMS results: SMS results are very useful for quickly checking LHC constraints without the need of event simulation. However, there exist severe limitations in the usability of the SMS interpretations provided by the collaborations, for example when only 1 mass plane is given for a 2-step topology. See these slides from the kick-off meeting for more details. Another issue is the limited coverage by the currently published SMS results (see e.g. 1707.09036) We'd like to improve on these issues.
    • Contacts: Suchita Kulkarni, Wolfgang Waltenberger

  • Delphes developments: several of the public recast codes and generally many pheno analyses rely on Delphes for the emulation of detector effects. Related with the point above, a generic treatment of long-lived particles (HSCP, displaced signatures, ...) within Delphes would be highly needed.
    • Contact: Michele Selvaggi

  • Open Data: Learn how to use it, make a physics case. (The released data is not yet that interesting for BSM, but none the less interesting to get experience and give feedback). See also presentation by Kati Lassila-Perini at the kick-off meeting.
    • Contact: Achim Geiser (CMS)

Examples of recast studies

  • This list of recent RecastingStudies may serve as a feedback to the experiments about the use of their results and the information they provide.

  • 'Best practice' guide: we remind all colleagues doing recasts that they, too, should provide their codes and supplementary info to the community/experiments (via HEPData where appropriate), to make it easier for others to repeat and/or re-use their results.


  • Searches for New Physics: Les Houches Recommendations for the Presentation of LHC Results, S. Kraml et al., Eur.Phys.J. C72 (2012) 1976, arXiv:1203.2489
  • Wish list from phenomenologists: material needed for implementing and validating LHC new physics searches in fast simulation tools, recast-wishlist-2014.pdf (30 Sep 2014)


Other initiatives or working groups

Related previous workshops

-- SabineKraml - 2020-12-08

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf recast-wishlist-2014.pdf r1 manage 91.2 K 2016-06-29 - 10:46 SabineKraml Wish list from phenomenologists: material needed for implementing and validating LHC new physics searches in fast simulation tools (30 Sep 2014)
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