we illustrate some of the other choices as variations compared to our central value:

We illustrate some of the other choices as variations

compared to our central value:

•αS(Mz) = 0.1156 → 0.1196

•New H1 ‘optimized’ parametrization

•New ZEUS-JETS ‘optimized parametrization

•Old ‘in-between’ parametrization with ‘humpy’ gluon solution

Comparison of central fit plus total uncertainties to variations with αs(Mz)=0.1156

OLD/NEW are the same apart from high-x for the sea.

STOP PRESS: the new NEW with fc=0.15 non-dynamic but Q20 and mc variation of fc, looks EXACTLy like OLD

Preliminary status

requested

HERA I PDFsHERA I PDFs

OLD NEW

Comparison of central fit plus total uncertainties to variations with αs(Mz)=0.1196

OLD/NEW are the same apart from high-x for the sea

STOP PRESS: the new NEW with fc=0.15 non-dynamic but Q20 and mc variation of fc, looks EXACTLy like OLD

NEWOLD

Comparison of central fit plus total uncertainties to parametrization variation using: New H1 optimised parametrization

Old/new are the same

Preliminary status

requested

HERA I PDFsHERA I PDFs

NEWOLD

Comparison of central fit plus total uncertainties to parametrization variation using: New H1 optimised parametrization

OLD/NEW very slightly different at high-x Dbar

STOP PRESS: the new NEW with fc=0.15 non-dynamic but Q20 and mc variation of fc, looks EXACTLy like OLD

NEWOLD

Comparison of central fit plus total uncertainties to parametrization variation using: New ZEUS-JETS optimised parametrization

OLD/NEW look the same

Preliminary status

requested

HERA I PDFsHERA I PDFs

NEWOLD

NEWOLD

Comparison of central fit plus total uncertainties to parametrization variation using: New ZEUS-JETS optimised parametrization

OLD/NEW look the same apart from very high-x Dbar

STOP PRESS: the new NEW with fc=0.15 non-dynamic but Q20 and mc variation of fc, looks EXACTLy like OLD

Comparison of central fit plus total uncertainties to parametrization variation using: the ‘humpy’solution for the h1/zeus parametrization.

At Q2=4 (right)GeV2 where the humpy structure is more visible

OLD/NEW look the same

Preliminary status

requested

NEWOLD