|
This page provides numerical table files for the
computation of CT18
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
standalone Fortran interface
and
demonstration program
, as well as the tables with interpolated values of the
QCD coupling alpha_s and PDFs.
A simple C++ interface for the CTEQ-TEA PDFs with
CTEQ6.6 or later can be found
here.
Parametrizations of CT18 PDFs are also available from the LHAPDF library, version 6. For backward compatibility, we also provide CT18 grids in the LHAPDF5 format. Note that, in order to call all 59 CT18 error PDF sets with LHAPDF 5.9.X, you must recompile LHAPDF with an updated CT wrapper. 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. |
| PDF set | Description and links to the table files | Authors or main contact | References | Date | Additional resources |
| CT18 NNLO |
*General-purpose
NNLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
Plots of L2 sensitivities
Additional figures |
|
CT18NF3 CT18NF4 CT18NF6 NNLO |
CT18 NNLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18 NLO |
*General-purpose
NLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al. |
arXiv:1912.10053 |
12/2019 |
Additional figures
|
|
CT18NF3 CT18NF4 CT18NF6 NLO |
CT18 NLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18Z NNLO |
*General-purpose
NNLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al.
|
arXiv:1912.10053 |
12/2019 |
Plots of L2 sensitivities
Additional figures |
|
CT18Z NF3 CT18Z NF4 CT18Z NF6 NNLO |
CT18Z NNLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ) , for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18Z 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18Z NLO |
*General-purpose
NLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al. |
arXiv:1912.10053 |
12/2019 |
Additional figures
|
|
CT18ZNF3 CT18ZNF4 CT18ZNF6 NLO |
CT18Z NLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18Z 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18A NNLO |
*General-purpose
NNLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al.
|
arXiv:1912.10053 |
12/2019 |
Additional figures |
|
CT18ANF3 CT18ANF4 CT18ANF6 NNLO |
CT18A NNLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18A 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18A NLO |
*General-purpose
NLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al. |
arXiv:1912.10053 |
12/2019 |
Additional figures
|
|
CT18ANF3 CT18ANF4 CT18ANF6 NLO |
CT18 NLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18X NNLO |
*General-purpose
NNLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al.
|
arXiv:1912.10053
|
12/2019 |
Additional figures |
|
CT18XNF3 CT18XNF4 CT18XNF6 NNLOX |
CT18X NNLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18X 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18X NLO |
*General-purpose
NLO central set + 58 eigenvector sets
(
LHAPDF6,
LHAPDF5
)
*PDF sets with a varied strong coupling alpha_s(M_Z) in the ranges 0.116-0.120 and 0.110-0.124. The recommended 90% C.L. uncertainty estimate is 0.116 - 0.120. |
T.-J. Hou et al. |
arXiv:1912.10053
|
12/2019 |
Additional figures
|
|
CT18XNF3 CT18XNF4 CT18XNF6 NLO |
CT18X NLO PDF sets in 3-flavor, 4-flavor and 6-flavor schemes ( LHAPDF6 ), for alternative choices of alpha_s(Q) in these schemes. These PDF sets are obtained by evolving the CT18X 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. |
T.-J. Hou et al.
|
arXiv:1912.10053 | 12/2019 |
README |
| CT18qed (recommended) |
*General-purpose
1 central + 58 Hessian sets + 2*8 low-Q2 sets (LHAPDF6)
Hessian sets are defined as 90% C.L., and low-Q2 sets are symmetrized and scaled to 90% C.L. Photon PDF are initialized at mu0=3 GeV (pQCD matching scale) with LUX formula and evolved to higher scales. |
K. Xie et al. |
arXiv:2106.10299 |
06/2021 |
|
| CT18qed1(.3)GeV |
*General-purpose
1 central + 58 Hessian sets + 2*8 low-Q2 sets (LHAPDF6)
Hessian sets are defined as 90% C.L., and low-Q2 sets are symmetrized and scaled to 90% C.L. Photon PDF are initialized at mu0=1.3 GeV (CT18 PDF starting scale) with LUX formula and evolved to higher scales |
K. Xie et al. |
arXiv:2106.10299 |
06/2021 |
|
| CT18lux |
*General-purpose
1 central + 58 Hessian sets + 2*8 low-Q2 sets (LHAPDF6)
Hessian sets are defined as 90% C.L., and low-Q2 sets are symmetrized and scaled to 90% C.L. Photon PDF are calculated with the LUX formalism at all scales. |
K. Xie et al. |
arXiv:2106.10299 |
06/2021 |
|
| CT18LO |
*General-purpose
1 central
(
LHAPDF6
)
|
M. Yan et al. |
arXiv:2205.00137 |
05/2022 |
Additional Figures |
| CT18FC | CT18FC NNLO fitted charm series; 4 model scenarios, each with 3 sets for Δχ2=0, 10, and 30; mem=0-2: CT18 BHPS3; mem=3-5: CT18 MBMC; mem=6-8: CT18 MCME; mem=9-11: CT18X BHPS3 (LHAPDF6) | M. Guzzi, T. J. Hobbs, K. Xie, J. Huston, P. Nadolsky, C.-P. Yuan |
arXiv:2211.01387 |
11/2022 |
|
| CT18qed neutron |
CT18qed neutron
(total,
elastic,
inelastic)
CT18qed proton (updated) (total, elastic, inelastic) |
K. Xie, B. Zhou, T.J. Hobbs |
arXiv:2305.10497 |
05/2023 |