Eur. Phys. J. C (2015) 75: 304
https://doi.org/10.1140/epjc/s10052-015-3480-z

Regular Article - Theoretical Physics

HERAFitter

Open source QCD fit project

¹ Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, 15738, Zeuthen, Germany
² Institute for High Energy Physics, 142281, Protvino, Moscow Region, Russia
³ Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany
⁴ Department of Physics, St. Petersburg State University, Ulyanovskaya 1, 198504, St. Petersburg, Russia
⁵ Nikhef, Science Park, Amsterdam, The Netherlands
⁶ Department of Physics, University of Oxford, Oxford, UK
⁷ Fachbereich C, Universität Wuppertal, Wuppertal, Germany
⁸ Rechenzentrum, Universität Wuppertal, Wuppertal, Germany
⁹ Aix Marseille Universite, CNRS/IN2P3, CPPM UMR 7346, 13288, Marseille, France
¹⁰ CEA, DSM/Irfu, CE-Saclay, Gif-sur-Yvette, France
¹¹ Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark
¹² School of Physics and Astronomy, University of Southampton, Southampton, UK
¹³ Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK
¹⁴ Department of Theoretical Physics, University of Oxford, Oxford, OX1 3NP, UK
¹⁵ FERMILAB, Batavia, IL, 60510, USA
¹⁶ Elementaire Deeltjes Fysica, Universiteit Antwerpen, 2020, Antwerp, Belgium
¹⁷ Joint Institute for Nuclear Research (JINR), Joliot-Curie 6, 141980, Dubna, Moscow Region, Russia
¹⁸ Southern Methodist University, Dallas, TX, USA
¹⁹ Max Planck Institut für Physik, Werner Heisenberg Institut, Föhringer Ring 6, München, Germany
²⁰ T. Kosciuszko University of Technology, Kraków, Poland
²¹ Laboratoire de Physique Nucléaire et de Hautes Energies, UPMC and Université, Paris-Diderot and CNRS/IN2P3, Paris, France
²² University College Dublin, Dublin 4, Ireland
²³ CERN, European Organization for Nuclear Research, Geneva, Switzerland
²⁴ Institut für Experimentelle Kernphysik, Karlsruhe, Germany
²⁵ CERN, PH-TH, 1211, Geneva 23, Switzerland
²⁶ Leave from LPTHE, CNRS UMR 7589, UPMC Univ. Paris 6, 75252, Paris, France
²⁷ Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
²⁸ Institute of Physics, Jagiellonian University, Reymonta 4, 30-059, Kraków, Poland
²⁹ PRISMA Cluster of Excellence, Institut für Physik (WA THEP), Johannes-Gutenberg-Universität, 55099, Mainz, Germany
³⁰ Department of Physics and Astronomy, University of Sussex, Sussex House, Brighton, BN1 9RH, UK
³¹ Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662, Warsaw, Poland
³² Institute for Particle Physics Phenomenology, Durham University, Durham, DH1 3LE, UK

^* e-mail: herafitter-help@desy.de

Received: 14 November 2014
Accepted: 19 May 2015
Published online: 2 July 2015

Abstract

HERAFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton and for many different kinds of analyses in Quantum Chromodynamics (QCD). It encodes results from a wide range of experimental measurements in lepton–proton deep inelastic scattering and proton–proton (proton–antiproton) collisions at hadron colliders. These are complemented with a variety of theoretical options for calculating PDF-dependent cross section predictions corresponding to the measurements. The framework covers a large number of the existing methods and schemes used for PDF determination. The data and theoretical predictions are brought together through numerous methodological options for carrying out PDF fits and plotting tools to help to visualise the results. While primarily based on the approach of collinear factorisation, HERAFitter also provides facilities for fits of dipole models and transverse-momentum dependent PDFs. The package can be used to study the impact of new precise measurements from hadron colliders. This paper describes the general structure of HERAFitter and its wide choice of options.