NNPDF3.1 alphas

Precision determination of the strong coupling constant within a global PDF analysis

Summary

We present a determination of the strong coupling constant \alpha_s(m_Z) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the Z p_T distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology – the correlated replica method – which allows for a simultaneous determination of \alpha_s and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find \alpha_s(m_Z) = 0.1185 \pm 0.0005^\text{(exp)}\pm 0.0001^\text{(meth)}, showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N^3LO and beyond) from half the shift between the NLO and NNLO \alpha_s values, finding \Delta\alpha^{\rm th}_s =0.0011.

Paper: arXiv:1802.03398

The PDF sets are available for download below.​ The information needed in order to correlate the replicas is in the LHAPDF header of each replica file. For each individual .dat file, the index from the ‘FromMCReplica’ key in the header should be parsed and replicas for different alpha_s but same index should be grouped together.

Note that usage of these sets is subject to the caveat explained in arXiv:2001.04986

NLO

NNPDF31_nlo_as_0106_ascorr.tar.gz                  
NNPDF31_nlo_as_0108_ascorr.tar.gz                  
NNPDF31_nlo_as_0110_ascorr.tar.gz                  
NNPDF31_nlo_as_0112_ascorr.tar.gz                  
NNPDF31_nlo_as_0113_ascorr.tar.gz                  
NNPDF31_nlo_as_0114_ascorr.tar.gz                  
NNPDF31_nlo_as_0115_ascorr.tar.gz                  
NNPDF31_nlo_as_0116_ascorr.tar.gz                  
NNPDF31_nlo_as_0117_ascorr.tar.gz                  
NNPDF31_nlo_as_0118_ascorr.tar.gz                  
NNPDF31_nlo_as_0119_ascorr.tar.gz                  
NNPDF31_nlo_as_0120_ascorr.tar.gz                  
NNPDF31_nlo_as_0121_ascorr.tar.gz                  
NNPDF31_nlo_as_0122_ascorr.tar.gz                  
NNPDF31_nlo_as_0123_ascorr.tar.gz                  
NNPDF31_nlo_as_0124_ascorr.tar.gz                  
NNPDF31_nlo_as_0125_ascorr.tar.gz                  
NNPDF31_nlo_as_0126_ascorr.tar.gz                  
NNPDF31_nlo_as_0127_ascorr.tar.gz                  
NNPDF31_nlo_as_0128_ascorr.tar.gz                  
NNPDF31_nlo_as_0130_ascorr.tar.gz 

NNLO

NNPDF31_nnlo_as_0106_ascorr.tar.gz                 
NNPDF31_nnlo_as_0108_ascorr.tar.gz                 
NNPDF31_nnlo_as_0110_ascorr.tar.gz                 
NNPDF31_nnlo_as_0112_ascorr.tar.gz                 
NNPDF31_nnlo_as_0113_ascorr.tar.gz                 
NNPDF31_nnlo_as_0114_ascorr.tar.gz                 
NNPDF31_nnlo_as_0115_ascorr.tar.gz                 
NNPDF31_nnlo_as_0116_ascorr.tar.gz                 
NNPDF31_nnlo_as_0117_ascorr.tar.gz                 
NNPDF31_nnlo_as_0118_ascorr.tar.gz                 
NNPDF31_nnlo_as_0119_ascorr.tar.gz                 
NNPDF31_nnlo_as_0120_ascorr.tar.gz                 
NNPDF31_nnlo_as_0121_ascorr.tar.gz                 
NNPDF31_nnlo_as_0122_ascorr.tar.gz                 
NNPDF31_nnlo_as_0123_ascorr.tar.gz                 
NNPDF31_nnlo_as_0124_ascorr.tar.gz                 
NNPDF31_nnlo_as_0125_ascorr.tar.gz                 
NNPDF31_nnlo_as_0126_ascorr.tar.gz                 
NNPDF31_nnlo_as_0127_ascorr.tar.gz                 
NNPDF31_nnlo_as_0128_ascorr.tar.gz                 
NNPDF31_nnlo_as_0130_ascorr.tar.gz        

Note that these PDF sets correspond to one of the 3 batches presented in arXiv:1802.03398

 

A third custom PDF set not including top data was produced upon request of the CMS collaboration:
The PDF are available for download below

NOTOP NNLO

NNPDF31_nnlo_as_0110_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0113_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0114_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0115_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0116_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0117_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0118_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0119_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0120_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0121_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0122_ascorr_notop.tar.gz           
NNPDF31_nnlo_as_0124_ascorr_notop.tar.gz