CT14 parton distribution functions


This page provides numerical table files for the computation of CT14 leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) parton distribution functions.  They can be interpolated with the help of a NEW standalone Fortran interface and demonstration program, as well as the tables with interpolated values of the QCD coupling alpha_s and PDFs.

Parametrizations of CT14 PDFs are also available from the LHAPDF library, version 6. For backward compatibility, we also provide CT14 grids in the LHAPDF5 format. Note that, in order to call all 57 CT14 error PDF sets with LHAPDF 5.9.X, you must recompile LHAPDF with an updated CT wrapper.

A simple C++ interface for the CTEQ-TEA PDFs with CTEQ6.6 or later can be found here.

ATTENTION: The format of the PDF table files (with the extension .pds) and the Fortran interface were revised in 2012 to provide interpolation of the energy dependence of the QCD running coupling alpha_s using a table of alpha_s values stored inside the .pds file. The pre-2012 PDF table files are partly incompatible with the new format. They can be interpolated by the 2012 interface, but without computing alpha_s.

Available PDF sets

See the header of the Fortran interface for further explanations. 
PDF set
Description
and links to the table files
Authors or
main contact
References
Date
Additional resources
CT14 NNLO *General-purpose NNLO central set + 56 eigenvector sets

*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.111-0.123. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120.
S. Dulat et. al.
arXiv:1506.07443 06/2015
Additional figures
CT14 NNLO Monte-Carlo NNLO central set + 1000 Monte-Carlo replicas for alpha_s(M_Z)=0.118 *PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.111-0.123. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. T.-J. Hou et. al.
arXiv:1607.06066 07/2016
Additional figures, MCGEN program for replica generation
CT14HERA2 NNLO NNLO central set + 56 eigenvector sets
T.-J. Hou  et. al. arXiv:1609.07968 09/2016 Additional figure
CT14NF3
CT14NF4
CT14NF6
NNLO
CT14 NNLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes, for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT14 NNLO parametrizations (obtained in the variable flavor scheme) from the initial scale Q0 to higher Q values using the 3-flavor, 4-flavor or 6-flavor DGLAP evolution. See README in the .zip file for further explanations. S. Dulat et. al. arXiv:1506.07443 06/2015

CT14IC
NNLO
* Four sets of CT14 intrinsic charm PDFs; at NNLO
S. Dulat et. al.
TBA 06/2015

CT14 NLO *General-purpose NLO central set + 56 eigenvector sets

*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.111-0.123. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120.
S. Dulat et. al. TBA 06/2015

CT14 NLO Monte-Carlo NLO central set + 1000 Monte-Carlo replicas for alpha_s(M_Z)=0.118 *PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.111-0.123. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. T.-J. Hou et. al.
arXiv:1607.06066 07/2016
Additional figures, MCGEN program for replica generation
CT14HERA2 NLO NLO central set + 56 eigenvector sets
T.-J. Hou  et. al. arXiv:1609.07968 09/2016
CT14NF3
CT14NF4
CT14NF6
NLO
CT14 NLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes, for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT14 NLO parametrizations (obtained in the variable flavor scheme) from the initial scale Q0 to higher Q values using the 3-flavor, 4-flavor or 6-flavor DGLAP evolution. See README in the .zip file for further explanations. S. Dulat et. al. TBA 06/2015

Additional figures
CT14 LO *General-purpose LO central sets

S. Dulat et. al. TBA 06/2015

CT14NF3
CT14NF4
CT14NF6
LO
CT14 LO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes, for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT14 LO parametrizations (obtained in the variable flavor scheme) from the initial scale Q0 to higher Q values using the 3-flavor, 4-flavor or 6-flavor DGLAP evolution. See README in the .zip file for further explanations. S. Dulat et. al. TBA 06/2015
CT14qed The 31 sets of  CT14qed PDFs for proton and neutron, respectively. They are obtained by evolving the PDFs at LO in the QED interaction and at NLO in the QCD interaction from the initial scale Q0 , where they are based on the CT14 NLO PDFs. The photon PDF includes the inelastic component only, in which the hadron dissociates, and it is described by a two-parameter ansatz, coming from radiation off the valence quarks. (The needed Fortran codes are included in the zip file. See README in the .zip file for further explanations.)

We also provide the CT14qed PDF files in the format of  LHAPDF version 6 and LHAPDF version 5.

C. Schmidt  et. al. arXiv:1509.02905 12/2015
CT14qed_inc The 31 sets of  CT14qed_inc PDFs for proton and neutron, respectively. They are obtained by evolving the PDFs at LO in the QED interaction and at NLO in the QCD interaction from the initial scale Q0 , where they are based on the CT14 NLO PDFs. The photon PDF in the proton is inclusive, including both inelastic and elastic contributions, and at the initial scale it is equal to the sum of the (inelastic) CT14qed and the elastic component derived from the Equivalent Photon Approximation. The photon PDF in the neutron is identical to CT14qed, since there is no elastic component for the neutron.  (The needed Fortran codes are included in the zip file. See README in the .zip file for further explanations.)

We also provide the CT14qed_inc PDF files in the format of  LHAPDF version 6 and LHAPDF version 5.

C. Schmidt  et. al. arXiv:1509.02905 05/2016

Previous families of PDFs: CTEQ10 and CTEQ6-CTEQ6.6
Web support:
Tie-Jiun Hou (tiejiunh at mail.smu.edu)
Pavel Nadolsky (nadolsky at smu.edu)
C.-P. Yuan (yuan at pa.msu.edu)

This website is partially supported by the U.S. National Science Foundation under Grant No. PHY-0855561 and PHY-1417326.