LHAPDF6: parton density access in the LHC precision era

By Andy Buckley, J. Ferrando, Seth Lloyd, Karl Nordström, B. Page, Martin Rüfenacht, M. Schönherr, Graeme Watt. The European Physical Journal C, 2014

1,807 citations recorded by the source corpus.

The Fortran LHAPDF library has been a long-term workhorse in particle physics, providing standardised access to parton density functions for experimental and phenomenological purposes alike, following on from the venerable PDFLIB package. During Run 1 of the LHC, however, several fundamental limitations in LHAPDF’s design have became deeply problematic, restricting the usability of the library for important physics-study procedures and providing dangerous avenues by which to silently obtain incorrect results. In this paper we present the LHAPDF 6 library, a ground-up re-engineering of the PDFLIB/LHAPDF paradigm for PDF access which removes all limits on use of concurrent PDF sets, massively reduces static memory requirements, offers improved CPU performance, and fixes fundamental bugs in multi-set access to PDF metadata. The new design, restricted for now to interpolated PDFs, uses centralised numerical routines and a powerful cascading metadata system to decouple software releases from provision of new PDF data and allow completely general parton content. More than 200 PDF sets have been migrated from LHAPDF 5 to the new universal data format, via a stringent quality control procedure. LHAPDF 6 is supported by many Monte Carlo generators and other physics programs, in some cases via a full set of compatibility routines, and is recommended for the demanding PDF access needs of LHC Run 2 and beyond.

Subfields: Computer Networks and Communications, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3378646dba1963fc2b94ac31498ebf95ea15b8af

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Computer Networks and Communications

In Nuclear and High Energy Physics

Citations in the corpus

The automation of next-to-leading order electroweak calculations (2018, background): “masses as explained in sect.5.4{ see in particular eq. (5.59) and the discussion given there. The PDFs are the central ones of the LUXqed plus PDF4LHC15 nnlo 100 set [109,110], extracted from LHAPDF6 [111] with number 82000; these are associated with S (m Z) = 0:118; (6.10) with a three-loop running”
Illuminating the photon content of the proton within a global PDF analysis (2017, methodology): “1luxQED sets are available via the LHAPDF6 interface [135]: NNPDF31_nlo_as_0118_luxqed NNPDF31_nnlo_as_0118_luxqed while the FiatLux library, an open-source C++ implementation of the LUXqed formalism, can be obtained from:”
Herwig 7.0/Herwig++ 3.0 release note (2015, background): “Further requirements are BOOST [11], gsl [12], fastjet [13] and LHAPDF [14], while a number of other dependencies are necessary in order to fully exploit the program’s capabilities.”
Event generation with Sherpa 2.2 (2019, methodology): “In addition, SHERPA can be built with an interface to the LHAPDF library [161, 162], allowing the user ample choice in particular of proton PDFs, including their respective error and variational sets.”
New developments in FeynCalc 9.0 (2016, background): “HEPMath, however, also contains built-in interfaces to LoopTools [17] and LHAPDF [29] that are missing in the two other packages.”
Herwig 7.2 release note (2019, background): “ystem which we will summarize below. Please refer to the online documentation for a fully detailed description or contact the authors. 9.1 SaS Parton Distribution Functions As version 6 of the LHAPDF [24] package does not contain any parton distributions for the partons inside resolved photons the F”
Higgs Physics at the HL-LHC and HE-LHC (2019, methodology): “The simulation of the charged Higgs associated production, t[b]H±, is done at fixed order in NLO while the SM backgrounds are done at LO (which are then normalised to their NLO values) using MadGraph interfaced with LHAPDF [118] and PYTHIA8 [319] which handles the showering and hadronisation of the ”
The PDF4LHC report on PDFs and LHC data: Results from Run I and preparation for Run II (2015, background): “0 PDFs are available on LHAPDF6 as sets of 100 replicas.”
Reweighting QCD matrix-element and parton-shower calculations (2016, methodology): “This [PDF]-notation only works with PDFs interfaced through Lhapdf6 [82].”
Physics at a 100 TeV pp collider: Higgs and EW symmetry breaking studies (2016, methodology): “17 The invariant mass of the photon pair is required to be in a small window around the measured Higgs boson mass mγγ ∈ [124, 126] GeV.”
The photon content of the proton (2017, methodology): “Previous results on the photon PDF include MRST2004qed [17], NNPDF23 qed [18] and CT14qed inc [19] (all available within LHAPDF [20]) and the HKR16 set [21].”