metapdf is hosted by Hepforge, IPPP Durham

META PDFs (for LHC applications)

Jun Gao, Joey Huston, Pavel Nadolsky

Southern Methodist University

Michigan State University

Introduction

META PDFs project aim to provide ``best'' fits for the central and error predictions of unpolarized parton distribution functions (PDFs) of proton, focusing on the LHC applications. Based on the meta data from various PDF fitting groups, the META PDFs combine selected PDF measurements while minimizing possible bias from individual groups. The META PDFs can potentially serve as an alternative to the PDF4LHC recommendations, and simplify the theoretical calculations and experimental analyses for the PDF inputs.

Currently (v1.0) we only provide META PDFs at Next-to-Next-to-Leading order in QCD by combining the PDFs from CT10, MSTW2008, and NNPDF2.3. Version 1.0 consists of one regular set (best+100 error PDFs), another set specified for SM Higgs boson study, and two more PDFs (αs(Mz) =0.116 and 0.120) for calculating αs uncertainties.

Sources

Version 1.0
LHAPDF5(grid files) metav10-lha5.tar.gz [26MB, 12-05-2013]
LHAPDF6(grid files) metav10-lha6.tar.gz [60MB, 12-07-2013]
Standalone Fortran (interface) metav10-for.tar.gz [16KB, 12-05-2013]
Standalone C++ (interface) metav10-cpp.tar.gz [20KB, 12-05-2013]
Mathematica (interface) notebook in nCTEQ webpage
PDS (table files for interfaces) metav10-pds.tar.gz [26MB, 12-05-2013]

Reference

1. arXiv:1401.0013 [hep-ph], Jun Gao, Pavel Nadolsky.

Please direct to jung@smu.edu or nadolsky@physics.smu.edu for questions.

Selected Figures

1, Comparison of META PDFs with other NNLO PDFs


           
           
           
2. Predictions for SM Higgs cross sections from META PDFs

The first 6 eigenvectors of LHCH set are good enough to reproduce uncertainties
including correlations of all the Higgs cross sections shown here.

Select PDF set:


   
   
3. Comparison of fitted PDFs with input PDFs

Select PDF groups:


           
           
           
4. Fit of individual PDF replicas

Select PDF groups:


           
           
           
5. META parameters for default NNLO PDFs

Select parameter:


           
           
           
6. Confidence intervals of parameters of META PDFs

Select parameter:


           
           
           
7. Parameters of META PDFs (left), input PDFs (right), for arbitrary combinations

Select parameter:


       
8, LHC predictions, input PDF vs. fitted PDF

           
           
           
           
           
           
               
               
9, LHC predictions, input PDF vs. META PDF

           
           
           
           
           
           
               
               
10, Constrained sum rules