pyhf is a pure-python implementation of the widely-used HistFactory p.d.f. template described in [CERN-OPEN-2012-016]. It also includes interval estimation is based on the asymptotic formulas of “Asymptotic formulae for likelihood-based tests of new physics” [arxiv:1007.1727]. The aim is also to support modern computational graph libraries such as PyTorch and TensorFlow in order to make use of features such as autodifferentiation and GPU acceleration.

GitHub Project DOI JOSS DOI Scikit-HEP NSF-1836650

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Recent Talks and Tutorials

SciPy 2020 talk YouTube

Use in Publications

Updating list of citations and use cases of pyhf:

  • Jean-Loup Tastet, Oleg Ruchayskiy, and Inar Timiryasov. Reinterpreting the ATLAS bounds on heavy neutral leptons in a realistic neutrino oscillation model. July 2021. arXiv:2107.12980.
  • ATLAS Collaboration. Search for chargino–neutralino pair production in final states with three leptons and missing transverse momentum in s√=13 TeV pp collisions with the ATLAS detector. June 2021. arXiv:2106.01676.
  • Belle II Collaboration. Search for B⁺→ K⁺νν̅ decays using an inclusive tagging method at Belle II. Contribution to the 2021 EW session of the 55th Rencontres de Moriond. May 2021. arXiv:2105.05754.
  • Belle II Collaboration. Search for B⁺→ K⁺νν̅ decays using an inclusive tagging method at Belle II. Apr 2021. arXiv:2104.12624.
  • Andrei Angelescu, Damir Bečirević, Darius A. Faroughy, Florentin Jaffredo, and Olcyr Sumensari. On the single leptoquark solutions to the B-physics anomalies. Mar 2021. arXiv:2103.12504.
  • Rodolfo Capdevilla, Federico Meloni, Rosa Simoniello, and Jose Zurita. Hunting wino and higgsino dark matter at the muon collider with disappearing tracks. Feb 2021. arXiv:2102.11292.
  • Vincenzo Cirigliano, Kaori Fuyuto, Christopher Lee, Emanuele Mereghetti, and Bin Yan. Charged Lepton Flavor Violation at the EIC. Feb 2021. arXiv:2102.06176.
  • Jack Y. Araz and others. Proceedings of the second MadAnalysis 5 workshop on LHC recasting in Korea. Mod. Phys. Lett. A, 36(01):2102001, 2021. arXiv:2101.02245, doi:10.1142/S0217732321020016.
  • Simone Amoroso, Deepak Kar, and Matthias Schott. How to discover QCD Instantons at the LHC. Eur. Phys. J. C, 81(7):624, Dec 2020. arXiv:2012.09120, doi:10.1140/epjc/s10052-021-09412-1.
  • Wolfgang Waltenberger, André Lessa, and Sabine Kraml. Artificial Proto-Modelling: Building Precursors of a Next Standard Model from Simplified Model Results. Dec 2020. arXiv:2012.12246, doi: 10.1007/JHEP03(2021)207.
  • Gaël Alguero, Jan Heisig, Charanjit K. Khosa, Sabine Kraml, Suchita Kulkarni, Andre Lessa, Philipp Neuhuber, Humberto Reyes-González, Wolfgang Waltenberger, and Alicia Wongel. New developments in SModelS. In Tools for High Energy Physics and Cosmology. Dec 2020. arXiv:2012.08192.
  • Matthew Feickert, Lukas Heinrich, and Giordon Stark. Likelihood preservation and statistical reproduction of searches for new physics. EPJ Web Conf., Nov 2020. doi:10.1051/epjconf/202024506017.
  • Gaël Alguero, Sabine Kraml, and Wolfgang Waltenberger. A SModelS interface for pyhf likelihoods. Sep 2020. arXiv:2009.01809.
  • ATLAS Collaboration. Search for new phenomena in events with two opposite-charge leptons, jets and missing transverse momentum in pp collisions at s√=13 TeV with the ATLAS detector. Geneva, Aug 2020. URL:
  • Jeffrey Krupa and others. GPU coprocessors as a service for deep learning inference in high energy physics. July 2020. arXiv:2007.10359.
  • Charanjit K. Khosa, Sabine Kraml, Andre Lessa, Philipp Neuhuber, and Wolfgang Waltenberger. SModelS database update v1.2.3. LHEP, 158:2020, May 2020. arXiv:2005.00555, doi:10.31526/lhep.2020.158.
  • Waleed Abdallah and others. Reinterpretation of LHC Results for New Physics: Status and Recommendations after Run 2. 2020. arXiv:2003.07868.
  • G. Brooijmans and others. Les Houches 2019 Physics at TeV Colliders: New Physics Working Group Report. In 2020. arXiv:2002.12220.
  • Andrei Angelescu, Darius A. Faroughy, and Olcyr Sumensari. Lepton Flavor Violation and Dilepton Tails at the LHC. Eur. Phys. J. C, 80(7):641, 2020. arXiv:2002.05684, doi:10.1140/epjc/s10052-020-8210-5.
  • B.C. Allanach, Tyler Corbett, and Maeve Madigan. Sensitivity of Future Hadron Colliders to Leptoquark Pair Production in the Di-Muon Di-Jets Channel. Eur. Phys. J. C, 80(2):170, 2020. arXiv:1911.04455, doi:10.1140/epjc/s10052-020-7722-3.
  • J. Alison and others. Higgs boson potential at colliders: status and perspectives. In 2019. arXiv:1910.00012.
  • ATLAS Collaboration. Reproducing searches for new physics with the ATLAS experiment through publication of full statistical likelihoods. Geneva, Aug 2019. URL:
  • Johann Brehmer, Felix Kling, Irina Espejo, and Kyle Cranmer. MadMiner: Machine learning-based inference for particle physics. Comput. Softw. Big Sci., 4(1):3, 2020. arXiv:1907.10621, doi:10.1007/s41781-020-0035-2.
  • Lukas Heinrich, Holger Schulz, Jessica Turner, and Ye-Ling Zhou. Constraining A₄ Leptonic Flavour Model Parameters at Colliders and Beyond. 2018. arXiv:1810.05648.

Published Likelihoods

Updating list of HEPData entries for publications using HistFactory JSON likelihoods:

  • Search for trilepton resonances from chargino and neutralino pair production in s√=13 TeV pp collisions with the ATLAS detector. 2020. doi:10.17182/hepdata.99806.
  • Search for displaced leptons in s√=13 TeV pp collisions with the ATLAS detector. 2020. doi:10.17182/hepdata.98796.
  • Search for squarks and gluinos in final states with same-sign leptons and jets using 139 fb−1 of data collected with the ATLAS detector. 2020. doi:10.17182/hepdata.91214.
  • Search for direct production of electroweakinos in final states with one lepton, missing transverse momentum and a Higgs boson decaying into two b-jets in (pp) collisions at s√=13 TeV with the ATLAS detector. 2020. doi:10.17182/hepdata.90607.
  • Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in s√ = 13 TeV pp collisions with the ATLAS detector. 2019. doi:10.17182/hepdata.91127.
  • Search for direct stau production in events with two hadronic τ-leptons in s√=13 TeV pp collisions with the ATLAS detector. 2019. doi:10.17182/hepdata.92006.
  • Search for bottom-squark pair production with the ATLAS detector in final states containing Higgs bosons, b-jets and missing transverse momentum. 2019. doi:10.17182/hepdata.89408.