The NNPDF collaboration
The NNPDF collaboration performs research in the field of high-energy physics. The NNPDF collaboration determines the structure of the proton using contemporary methods of artificial intelligence. A precise knowledge of the so-called Parton Distribution Functions (PDFs) of the proton, which describe their structure in terms of their quark and gluon constituents, is a crucial ingredient of the physics program of the Large Hadron Collider of CERN.
The NNPDF code
The scientific output of the collaboration is freely available to the public through the arXiv, journal repositories, and software repositories. Along with this online documentation, we release the NNPDF code, used to produce the latest family of PDFs from NNPDF: NNPDF4.0. The code is made available as an open-source package together with the user-friendly examples and an extensive documentation presented here.
The code can be used to produce the ingredients needed for PDF fits, to run the fits themselves, and to analyse the results. This is the first framework used to produce a global PDF fit made publicly available, enabling for detailed external validation and reproducibility of the NNPDF4.0 analysis. Moreover, the code enables the user to explore a number of phenomenological applications, such as the assessment of the impact of new experimental data on PDFs, the effect of changes in theory settings on the resulting PDFs and a fast quantitative comparison between theoretical predictions and experimental data over a broad range of observables.
If you are a new user head along to getstarted and check out the Tutorials.
The NNPDF team
The NNPDF collaboration is currently composed by the following members:
Richard D. Ball - University of Edinburgh
Stefano Carrazza - Universita’ degli Studi di Milano
Juan Cruz-Martinez - Tif Lab, Dipartimento di Fisica, Università di Milano and INFN
Luigi Del Debbio - University of Edinburgh
Stefano Forte - Tif Lab, Dipartimento di Fisica, Università di Milano and INFN
Tommaso Giani - University of Edinburgh
Shayan Iranipour - University of Cambridge
Zahari Kassabov - University of Cambridge
Rabah Abdul Khalek - Nikhef Theory Group and VU University
José Ignacio Latorre - Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, United Arab Emirates and Center for Quantum Technologies, National University of Singapore
Emanuele R. Nocera - University of Edinburgh
Rosalyn Pearson - University of Edinburgh
Juan Rojo - Nikhef Theory Group and VU University
Roy Stegeman - Tif Lab, Dipartimento di Fisica, Università di Milano and INFN
Christopher Schwan - Tif Lab, Dipartimento di Fisica, Università di Milano and INFN
Maria Ubiali - University of Cambridge
Cameron Voisey - University of Cambridge
Michael Wilson - University of Edinburgh
Former members of the NNPDF collaboration include
Valerio Bertone
Francesco Cerutti
Christopher S. Deans
Alberto Guffanti
Patrick Groth-Merrild
Nathan P. Hartland
Andrea Piccione
Luca Rottoli
Emma Slade
The NNPDF publications
“Future tests of parton distributions”, Juan Cruz-Martinez, Stefano Forte, Emanuele R. Nocera [CMFN21]
“Deuteron Uncertainties in the Determination of Proton PDFs”, Richard D. Ball, Emanuele R. Nocera, Rosalyn L. Pearson, [BNP21]
“Parton Distribution Functions”, Stefano Carrazza, Stefano Forte [FC20]
“Phenomenology of NNLO jet production at the LHC and its impact on parton distributions”, Rabah Abdul Khalek, Stefano Forte, Thomas Gehrmann, Aude Gehrmann-De Ridder, Tommaso Giani, Nigel Glover, Alexander Huss, Emanuele R. Nocera, Joao Pires, Juan Rojo, Giovanni Stagnitto [AK+20]
“Why αs Cannot be Determined from Hadronic Processes without Simultaneously Determining the Parton Distributions”, Stefano Forte, Zahari Kassabov, [FK20]
“Single top production in PDF fits”, Emanuele R. Nocera, Maria Ubiali, Cameron Voisey, [NUV20]
“Parton Distributions with Theory Uncertainties: General Formalism and First Phenomenological Studies”, Rabah Abdul Khalek, Richard D. Ball, Stefano Carrazza, Stefano Forte, Tommaso Giani, Zahari Kassabov, Rosalyn L. Pearson, Emanuele R. Nocera, Juan Rojo, Luca Rottoli, Maria Ubiali, Cameron Voisey and Michael Wilson [AK+19a]
“Nuclear Parton Distributions from Lepton-Nucleus Scattering and the Impact of an Electron-Ion Collider”, Rabah Abdul Khalek, Jacob J. Ethier, Juan Rojo, [AKER19]
“A First Determination of Parton Distributions with Theoretical Uncertainties”, Rabah Abdul Khalek, Richard D. Ball, Stefano Carrazza, Stefano Forte, Tommaso Giani, Zahari Kassabov, Emanuele R. Nocera, Rosalyn L. Pearson, Juan Rojo, Luca Rottoli, Maria Ubiali, Cameron Voisey, and Michael Wilson [AK+19b]
“Towards a new generation of parton densities with deep learning models”, Stefano Carrazza and Juan Cruz-Martinez [CCM19]
“Parton distributions from high-precision collider data”, Richard D. Ball, Valerio Bertone, Stefano Carrazza, Luigi Del Debbio, Stefano Forte, Patrick Groth-Merrild, Alberto Guffanti, Nathan P. Hartland, Zahari Kassabov, Jose I. Latorre, Emanuele R. Nocera, Juan Rojo, Luca Rottoli, Emma Slade, and Maria Ubiali [B+17]
Contents
- Getting started
- Fitting code:
n3fit
- Code for data: validphys
- Handling experimental data: Buildmaster
- Storage of data and theory predictions
- Theory
- Chi square figures of merit
- Contributing guidelines and tools
- Releases and compatibility policy
- Continuous integration and deployment
- Servers
- External codes
- Tutorials
Bibliography
- AKER19
Rabah Abdul Khalek, Jacob J. Ethier, and Juan Rojo. Nuclear parton distributions from lepton-nucleus scattering and the impact of an electron-ion collider. Eur. Phys. J. C, 79(6):471, 2019. arXiv:1904.00018, doi:10.1140/epjc/s10052-019-6983-1.
- AK+19a
Rabah Abdul Khalek and others. A first determination of parton distributions with theoretical uncertainties. Eur. Phys. J., C:79:838, 2019. arXiv:1905.04311, doi:10.1140/epjc/s10052-019-7364-5.
- AK+19b
Rabah Abdul Khalek and others. Parton Distributions with Theory Uncertainties: General Formalism and First Phenomenological Studies. Eur. Phys. J. C, 79(11):931, 2019. arXiv:1906.10698, doi:10.1140/epjc/s10052-019-7401-4.
- AK+20
Rabah Abdul Khalek and others. Phenomenology of NNLO jet production at the LHC and its impact on parton distributions. Eur. Phys. J. C, 80(8):797, 2020. arXiv:2005.11327, doi:10.1140/epjc/s10052-020-8328-5.
- BDDF+10
Richard D. Ball, Luigi Del Debbio, Stefano Forte, Alberto Guffanti, Jose I. Latorre, Juan Rojo, and Maria Ubiali. Fitting Parton Distribution Data with Multiplicative Normalization Uncertainties. JHEP, 05:075, 2010. arXiv:0912.2276, doi:10.1007/JHEP05(2010)075.
- BNP21
Richard D. Ball, Emanuele R. Nocera, and Rosalyn L. Pearson. Deuteron Uncertainties in the Determination of Proton PDFs. Eur. Phys. J. C, 81(1):37, 2021. arXiv:2011.00009, doi:10.1140/epjc/s10052-020-08826-7.
- B+17
Richard D. Ball and others. Parton distributions from high-precision collider data. Eur. Phys. J. C, 77(10):663, 2017. arXiv:1706.00428, doi:10.1140/epjc/s10052-017-5199-5.
- B+21
missing journal in nnpdf40code
- BGYZ16
Edmond L. Berger, Jun Gao, C. -P. Yuan, and Hua Xing Zhu. NNLO QCD Corrections to t-channel Single Top-Quark Production and Decay. Phys. Rev. D, 94(7):071501, 2016. arXiv:1606.08463, doi:10.1103/PhysRevD.94.071501.
- BGZ17
Edmond L. Berger, Jun Gao, and Hua Xing Zhu. Differential Distributions for t-channel Single Top-Quark Production and Decay at Next-to-Next-to-Leading Order in QCD. JHEP, 11:158, 2017. arXiv:1708.09405, doi:10.1007/JHEP11(2017)158.
- BCE+16
Radja Boughezal, John M. Campbell, R. Keith Ellis, Christfried Focke, Walter T. Giele, Xiaohui Liu, and Frank Petriello. Z-boson production in association with a jet at next-to-next-to-leading order in perturbative QCD. Phys. Rev. Lett., 116(15):152001, 2016. arXiv:1512.01291, doi:10.1103/PhysRevLett.116.152001.
- BFLP15
Radja Boughezal, Christfried Focke, Xiaohui Liu, and Frank Petriello. $W$-boson production in association with a jet at next-to-next-to-leading order in perturbative QCD. Phys. Rev. Lett., 115(6):062002, 2015. arXiv:1504.02131, doi:10.1103/PhysRevLett.115.062002.
- BGPU17
Radja Boughezal, Alberto Guffanti, Frank Petriello, and Maria Ubiali. The impact of the LHC Z-boson transverse momentum data on PDF determinations. JHEP, 07:130, 2017. arXiv:1705.00343, doi:10.1007/JHEP07(2017)130.
- BLP15
Radja Boughezal, Xiaohui Liu, and Frank Petriello. $N$-jettiness soft function at next-to-next-to-leading order. Phys. Rev. D, 91(9):094035, 2015. arXiv:1504.02540, doi:10.1103/PhysRevD.91.094035.
- BLP16
Radja Boughezal, Xiaohui Liu, and Frank Petriello. Phenomenology of the Z-boson plus jet process at NNLO. Phys. Rev. D, 94(7):074015, 2016. arXiv:1602.08140, doi:10.1103/PhysRevD.94.074015.
- CEW17
John M. Campbell, R. Keith Ellis, and Ciaran Williams. Direct Photon Production at Next-to–Next-to-Leading Order. Phys. Rev. Lett., 118(22):222001, 2017. [Erratum: Phys.Rev.Lett. 124, 259901 (2020)]. arXiv:1612.04333, doi:10.1103/PhysRevLett.118.222001.
- CRSW18
John M. Campbell, Juan Rojo, Emma Slade, and Ciaran Williams. Direct photon production and PDF fits reloaded. Eur. Phys. J. C, 78(6):470, 2018. arXiv:1802.03021, doi:10.1140/epjc/s10052-018-5944-4.
- CCM19
Stefano Carrazza and Juan Cruz-Martinez. Towards a new generation of parton densities with deep learning models. Eur. Phys. J. C, 79(8):676, 2019. arXiv:1907.05075, doi:10.1140/epjc/s10052-019-7197-2.
- CFKR16
Stefano Carrazza, Stefano Forte, Zahari Kassabov, and Juan Rojo. Specialized minimal PDFs for optimized LHC calculations. Eur. Phys. J. C, 76(4):205, 2016. arXiv:1602.00005, doi:10.1140/epjc/s10052-016-4042-8.
- CMFN21
Juan Cruz-Martinez, Stefano Forte, and Emanuele R. Nocera. Future tests of parton distributions. Acta Phys. Polon. B, 52:243, 2021. arXiv:2103.08606, doi:10.5506/APhysPolB.52.243.
- CGP17
J Currie, E. W. N. Glover, and J Pires. Next-to-Next-to Leading Order QCD Predictions for Single Jet Inclusive Production at the LHC. Phys. Rev. Lett., 118(7):072002, 2017. arXiv:1611.01460, doi:10.1103/PhysRevLett.118.072002.
- CGDRG+17
James Currie, Aude Gehrmann-De Ridder, Thomas Gehrmann, E. W. N. Glover, Alexander Huss, and Joao Pires. Precise predictions for dijet production at the LHC. Phys. Rev. Lett., 119(15):152001, 2017. arXiv:1705.10271, doi:10.1103/PhysRevLett.119.152001.
- CFM13
Michał Czakon, Paul Fiedler, and Alexander Mitov. Total Top-Quark Pair-Production Cross Section at Hadron Colliders Through $O(\alpha ^4_S)$. Phys. Rev. Lett., 110:252004, 2013. arXiv:1303.6254, doi:10.1103/PhysRevLett.110.252004.
- CHM+17
Michał Czakon, Nathan P. Hartland, Alexander Mitov, Emanuele R. Nocera, and Juan Rojo. Pinning down the large-x gluon with NNLO top-quark pair differential distributions. JHEP, 04:044, 2017. arXiv:1611.08609, doi:10.1007/JHEP04(2017)044.
- CHM17
missing journal in Czakon:2017dip
- DDKM11
Ansgar Denner, Stefan Dittmaier, Tobias Kasprzik, and Alexander Muck. Electroweak corrections to dilepton + jet production at hadron colliders. JHEP, 06:069, 2011. arXiv:1103.0914, doi:10.1007/JHEP06(2011)069.
- FC20
missing journal in Forte:2020yip
- FK20
Stefano Forte and Zahari Kassabov. Why $\alpha _s$ cannot be determined from hadronic processes without simultaneously determining the parton distributions. Eur. Phys. J. C, 80(3):182, 2020. arXiv:2001.04986, doi:10.1140/epjc/s10052-020-7748-6.
- Gao18
Jun Gao. Massive charged-current coefficient functions in deep-inelastic scattering at NNLO and impact on strange-quark distributions. JHEP, 02:026, 2018. arXiv:1710.04258, doi:10.1007/JHEP02(2018)026.
- GSTW15
Jonathan Gaunt, Maximilian Stahlhofen, Frank J. Tackmann, and Jonathan R. Walsh. N-jettiness Subtractions for NNLO QCD Calculations. JHEP, 09:058, 2015. arXiv:1505.04794, doi:10.1007/JHEP09(2015)058.
- GLPQ11
Ryan Gavin, Ye Li, Frank Petriello, and Seth Quackenbush. FEWZ 2.0: A code for hadronic Z production at next-to-next-to-leading order. Comput. Phys. Commun., 182:2388–2403, 2011. arXiv:1011.3540, doi:10.1016/j.cpc.2011.06.008.
- Kas19
Zahari Kassabov. Reportengine: A framework for declarative data analysis. February 2019. URL: https://doi.org/10.5281/zenodo.2571601, doi:10.5281/zenodo.2571601.
- NUV20
Emanuele R. Nocera, Maria Ubiali, and Cameron Voisey. Single Top Production in PDF fits. JHEP, 05:067, 2020. arXiv:1912.09543, doi:10.1007/JHEP05(2020)067.
- BallCarrazzaCruzMartinez+21
Richard D. Ball, Stefano Carrazza, Juan Cruz-Martinez, Luigi Del Debbio, Stefano Forte, Tommaso Giani, Shayan Iranipour, Zahari Kassabov, Jose I. Latorre, Emanuele R. Nocera, Rosalyn L. Pearson, Juan Rojo, Roy Stegeman, Christopher Schwan, Maria Ubiali, Cameron Voisey, and Michael Wilson. The Path to Proton Structure at One-Percent Accuracy. arXiv e-prints, pages arXiv:2109.02653, September 2021. arXiv:2109.02653.