H1prelim-11-042 ZEUS-prel-11-002 H1 and ZEUS |
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HERAPDF1.5 NNLO |
Reference |
Preliminary Moriond2011, March 2011
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Figures |
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Contact | V. Radescu, A. Cooper-Sarkar et al. |
Abstract | A preliminary NNLO QCD analysis is presented using the NC and CC inclusive
DIS cross sections obtained from the combination of the measurements from H1
and ZEUS based on the published HERA I and the preliminary HERA II data.
The HERAPDF1.5NNLO fit is performed in the NNLO DGLAP scheme as implemented in
the?evolution code QCDNUM 17. Heavy quarks are treated as massive using
the NNLO version of the Thorne-Roberts variable flavour number scheme.
In comparison to the most recent HERAPDF1.5 NLO, a more flexible
parameterisation for the present QCD fits has been chosen wich affects most
gluon distribution at low x. A full set of the PDF uncertainties for
HERAPDF1.5NNLO is determined. Experimental uncertainties, variation of model
parameters and assumptions on the parametrization of the PDFs are considered.
For the strong coupling constant a central value of alpha_s(M_Z)=0.1176
is used but a series of PDFs by varying alpha_s(M_Z) in the range
0.114 - 0.122 are also available. |
Links |
H1 and ZEUS combined results List of H1 papers
   
H1 internal information
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