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fast pQCD calculations for hadron-induced processes
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General concept

The fastNLO project provides computer code to create and evaluate fast interpolation tables of pre-computed coefficients in perturbation theory for observables in hadron-induced processes.

This allows fast theory predictions of these observables for arbitrary parton distribution functions (of regular shape), renormalization or factorization scale choices, and/or values of alpha_s(Mz) as e.g. needed in PDF fits or in systematic studies. Very time consuming complete recalculations are thus avoided.

May 7, 2017

First NNLO interpolation tables available

Courtesy of M. Czakon, D. Heymes, and A. Mitov the first fastNLO interpolation tables at NNLO are available for LHC ttbar production at 8 TeV, please see this article for details.
The new tables can be downloaded from the authors' web page. If you use these tables please follow the authors' requests for proper citation.
They can be evaluated with the previous fastNLO release 2.3.1-rev2212 or with the newly released version 2.3.1-rev2402. The results are identical.

May 7, 2017

New public prerelease 2.3.1-rev2402 of fastNLO Toolkit

Some major new developments are included in this release:
(Attention: compiler with C++11 support is mandatory!)
- In preparation of grid productions for NNLO calculations, many new features have been implemented with respect to fastNLO table mass production and their statistical combination. In particular, these are
- usage of the nnlo-bridge package (to be released) for filling fastNLO or APPLgrid interpolation grids from NNLOJET
- extension of the fastNLO table format (2.36.00, backwards compatible) to store statistical weight information for many new merging options addressing statistical fluctuations in NNLO grid productions
- steering-less initialisation possible in addition to steering files
- improved warmup file generation and check
- more options for distribution of x nodes
- Support of transparent writing/reading of gzipped tables tab.gz to reduce significantly the necessary disk space when storing large numbers of tables; requires the zlib compression library to be present;
- Includes new test suite to check installation 'make check'
- Includes basic example for a bi-directional interface between the C++ fastNLO toolkit and Fortran analysis / PDF fitting code (fortranext)
- The fastNLO table evaluation part is mostly unchanged, but has been complemented with more tools to manipulate tables like
- cutting out unused bins or multiplying bins by a set of factors (fnlo-tk-modify)
- concatenating separately calculated phase-space bins into one common table (fnlo-tk-cat)
- printing out normalised cross sections directly for tables set up with normalisation flag (fnlo-tk-cppread, fnlo-tk-yodaout)
- printing out partial cross sections for crosschecks, e.g. NLO contribution alone, or of cross section for all members of a PDF set (fnlo-tk-cppread)
- new merger with many new options for table combination (fnlo-tk-merge2)
- Issue reported by D. Maitre fixed
- Some issues in Python wrapper fixed
As usual, the new package can be downloaded from our code web pages.

March 14, 2017

Updated some Rivet links and point HepData links to new now.

March 6, 2017

New interpolation tables added

The following new tables have been added:
- Inclusive jets from CMS at 2.76 TeV.
- Inclusive jets from CMS at 8 TeV.

They can be downloaded here.

December 24, 2016

New interpolation tables added

Some new tables have been added in the meantime:
- Inclusive jets from CMS at 13 TeV. (2.76 and 8 TeV to come soon.)
- Inclusive jets table for STAR data at 0.2 TeV.

We wish you all a Merry Xmas and Happy New Year 2017

March 11, 2016

New public prerelease of fastNLO Toolkit

Some little issues fixed and:
- Add producer for ROOT files with xsections & uncertainties.
- Added executable fnlo-tk-statunc to derive statistical uncertainty from sample of calculations with equal weight.
- Installation adapted to new autotools-enabled QCDNUM versions. Old-style QCDNUM versions not supported anymore.
- Some adaptations for use in newer xFitter version.
- Some adaptations for use with mcgrid 2.0.
As usual, the new package can be downloaded from our code web pages.

September 10, 2015

New public prerelease of fastNLO Toolkit

Some little issues fixed and:
- PDF uncertainties calculable via fastNLO code or via LHAPDF6 (both not for HERAPDF). A struct with 3 vectors is returned giving x section and rel. lower and upper uncertainty.
- fnlo-tk-yodaout acquired an additional option for the fixed-order to be used, def. is NLO.
- Standard table info printout now also prints no. of x nodes.
- Improvements in table checking when merging/appending.
As usual, the new package can be downloaded from our code web pages.

August 25, 2015

New public prerelease of fastNLO Toolkit

Only some little issues have been fixed and improvements incorporated into this prerelease:
- Interface part to MCgrid v2.0 finalized.
- Option "IgnoreWarmupBinningCheck" added, avoids warmup binning check if set to true (useful for bin borders in pi etc.).
- An example to fill ROOT histograms from within fastNLO is provided (with input from Giannis Flouris)
- Rebuild problem in Doxygen documentation is fixed.
- Improved problem catch for ill-formatted tables.
- Added some more safety measures with respect to inf or nan entries.
- Improved logging handling.
As usual, the new package can be downloaded from our code web pages.

May 1, 2015

New public prerelease of fastNLO Toolkit

Major work went into this prelease:
- This prerelease is meant to work with the next release of MCgrid (> v1.2) and Sherpa to include all NLO processes available via this chain.
- A new executable fnlo-tk-yodaout has been conceived (including work by Stefanos Tyros) that provides YODA-formatted output for inclusion of fixed-oder table evaluations in Data/MC comparisons via Rivet. Foreseen to be used in MCplots.
- Up to triple differential observable binnings are supported, numerous Getter functions are provided.
- Functionality to derive scale and PDF uncertainties has been added and is used in fnlo-tk-yodaout
- fnlo-tk-config executable is provided for easier compiling/linking.
- A first version of Doxygen documentation is included.
- Method added to derive scale uncertainties.
- Numerous little issues fixed
In addition, the example interface and code for NLOjet++ with this toolkit has been further simplified. Both packages can be downloaded from our code web pages.

April 28, 2015

Updated talk list

The talk list has been updated with the latest presentations up to DIS15.

April 24, 2015

Compatibility update of fastNLO Reader

fastNLO_reader version 2.1.0, revision 2066:
Compatibility update for changes in next pre-release of fastNLO_toolkit:
- Up to 3-dimensional binnings are supported
- 7 subprocesses for LO hh->jets as used in toolkit is supported
- Internally used cross section units are rescaled to published units
The updated package can be downloaded here.

July 24, 2014

Small update of fastNLO Toolkit

Prerelease updated with small changes to eliminate some installation hiccups for the optional parts and to remove some additional warnings found by other compilers. The updated package can be downloaded here.

July 17, 2014

Public prerelease of new fastNLO Toolkit

The new fastNLO Toolkit provides a library with all functionality to create, fill, read, and evaluate interpolation tables in the fastNLO format. It comes with a much improved structure that allows other programs to be interfaced to fastNLO. In addition, an example interface and code how to use NLOjet++ with this toolkit is available. Both packages can be downloaded from our code web pages.

July 16, 2014

Finally: New calculations for H1 multijets available

New fastNLO tables for the recent measurement by H1 on multijet production [arXiv:1406.4709] are available as flexible-scale tables. They are complemented by further jet production tables in DIS that were previously distributed within the HERAFitter framework. They can be downloaded here.

April 26, 2014

fastNLO toolkit announced

The fastNLO toolkit is a new collection of tools to create and evaluate fastNLO tables. The development was specifically optimized to simplify interfacing fastNLO to NLO or NNLO programs. A pre-release of the fastNLO toolkit is available on request by the authors.

February 14, 2014

Bug fix release 1689 of fastnlo_reader:

Releases 1563 and 1567 of the fastnlo_reader did not properly change to a new LHAPDF set if another file was requested within the C++ code. The results of the very first call were not affected. This has been corrected in release 1689, see this page for more info and download.

January 28, 2014

Table fnl2222b_I1087342 for CMS inclusive forward jets uploaded:

See this page.

January 8, 2014

Missing optional header file added to latest release:

Release 1563 of the fastnlo_reader code was missing an optional header file. This has been added in release 1567, see this page for more info and download.

December 19, 2013

New release of fastnlo_reader code:

A new release of the fastnlo_reader code (1563) is available supporting alternative alpha_s evolutions, a Python interface and LHAPDF6. Please go to this page for more info and download.

December 6, 2013

CMS 3-jet ratio tables online

The CMS data on the 3-jet ratio measurement are available now from HEPDATA. The corresponding tables (numerator and denominator) are available here.

September 20-30, 2013

New code, tables, and plots available. More work is in progress:

A new release of the fastnlo_reader code (1488) is available. Please go to this page for more info and download.

Tevatron inclusive jets tables have been converted to be used with the new format. Please go to this page for an overview and download. There are more tables in the queue.

Update of "all jets plot" for 2013 available including 2011 ATLAS data at 2.76 TeV and 2011 CMS data at 7 TeV. See the Documentation tab.

May 13, 2013

Preliminary tables for the 2011 CMS inclusive jet and dijet mass cross sections:

The numbers of the tables are final, only some text comments inside the files and their final name and location on HepForge will be updated as soon as the final CMS publication reference is known. The tables can be found here CMS 2011 inclusive jets and here CMS 2011 dijet mass. They can be evaluated with the available fastNLO reader program/library here: fastNLO_reader_2.1.0_1360.

January 14, 2013

Micro update release version 2.1.0, revision 1360:

To avoid the problem of an uninitialized top PDF when accessing ABKM09 or ABM11 PDFs via Fortran in LHAPDF (versions 5.8.7 and 5.8.8), the top PDF has been set to zero explicitly in the Fortran reader. Otherwise one could observe crashes or - even worse - arbitrarily wrong cross sections. This problem was not present when using the C++ reader. As a consequence some differences between the reader programs can show up when using a PDF set with top PDFs > 0 like NNPDF 2.1 and scales Q > M_top. This bug has been fixed in LHAPDF version 5.8.9b1 such that the workaround could be deactivated. Use this Fortran reader revision 1360, download: fastNLO_reader_2.1.0_1360, ONLY with LHAPDF 5.8.9b1 or later when accessing PDF sets ABKM09 or ABM11 !

Example output for comparison using the CMS inclusive jets 2010 table: CTEQ66 C++ and Fortran, NNPDF 2.1 NNLO C++, Fortran rev. 1354 and Fortran rev. 1360.

December 21, 2012

New World's End Xmas Edition of generic table reader, in Fortran and C++, for fastNLO version 2 available!

Download: fastNLO_reader_2.1.0_1354

See the README file for instructions and the NEWS and ChangeLog for details on the updates. Running the example executables fnlo-cppread (or fnlo-fread for the Fortran version) with option -h explains the available options. The source file of the C++ reader contains detailed comments on its usage for personal adaptations. Please note that the C++ part now comes in the form of a library that can be linked to one owns personal code, e.g. as demonstrated with the example executable fnlo-cppread.

October 16, 2012

Recent talks added

Recent talks and links added to the Documentation section. Also, some small updates on the website layout and in the code section.

March 22, 2012


By mistake the tables for the ATLAS inclusive jets with jet sizes R=0.4 and R=0.6 had been exchanged! This is fixed now. One documentation line quoting the jet size within the tables and the corresponding links below have been corrected. So the ATLAS inclusive jet table for R=0.4 is called fnl1016 and for R=0.6 fnl1015. Many thanks to Jun Gao for pointing this out to us.

February 14, 2012

Generic table reader, in Fortran and C++, for new fastNLO version 2 available

Download: fastNLO_reader_2.1.0_1062
New v2 tables, including threshold corrections at default scale, for ATLAS Inclusive Jets, arXiv:1112.6297, with anti-kT jet sizes R=0.4 and R=0.6 available.

New v2 table as well as converted v14 table for CMS Inclusive Jets, Phys. Rev. Lett. 107 (2011) 132001, available; v2 table also includes 2-loop threshold corrections st default scale and, as proof of concept, the CMS non-perturbative correction factors as well as data points.

Logging output for comparison can be found here

ATLAS R=0.4, Fortran, ATLAS R=0.4, C++, ATLAS R=0.6, Fortran, ATLAS R=0.6, C++, CMS R=0.5, Fortran, CMS R=0.5, C++, CMS R=0.5, Fortran, converted from v14, CMS R=0.5, C++, converted from v14.

July 04, 2011

LHAPDF 5.8.5 installed ABKM09, CT10, NNPDF2.1_100, and HERAPDF1.0 PDFs added
CMS inclusive jets arXiv:1106.0208 and CMS dijet mass arXiv:1104.1693 added to interactive webinterface; matching code and tables available as well.

June 10, 2010

arXiv:0906.4819 and arXiv:1002.4594 have been added

Mailing list

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If you have any further questions or requests, please contact the authors at:

Daniel Britzger, Klaus Rabbertz, Georg Sieber, Fred Stober, Markus Wobisch
(send mail to the authors:

This work is supported by grant DE-SC0009859 from the U.S. Department of Energy. This work has received support within the project "Inclusive and Semi-Inclusive Constraints on the Parton Distributions at the LHC and the Study of Hard Processes" by the Helmholtz Alliance "Physics at the Terascale".

Last modified by rabbertz on: