Investigate model uncertainties OLD/NEW

1. Investigate model uncertaintiesOLD/NEW

2. NEW OLD Include only variation of charm mass and beauty mass mc:1.35→1.5 GeV and mb: 4.3 →5.0 GeV This model dependence was invisible – and its still invisible

3. NEW OLD Include only variation of charm mass and beauty mass mc:1.35→1.5 GeV and mb: 4.3 →5.0 GeV This model dependence was invisible – and its still invisible

4. NEW OLD Include only variation of strange fraction fs: 0.25 →0.40 Makes very little difference in the total Sea, but affects sea flavour break-up New/OLD look the same

5. NEW OLD Include only variation of strange fraction fs: 0.25 →0.40 Makes very little difference in the total Sea, but affects sea flavour break-up NEW/OLD look the same

6. NEW OLD Include only variation of charm fraction fc: 0.10 →0.20 OLD 0.07 → 0.11 NEW A smaller effect than fs: makes very little difference in the total Sea, but affects sea flavour break-up Couldn’t see it before- Can’t see it now!

7. NEW OLD NEW Include only variation of charm fraction fc: 0.10 →0.20 OLD 0.07 → 0.11 NEW A smaller effect than fs: makes very little difference in the total Sea, but affects sea flavour break-up This model dependence is smaller now as it should be! If you look at flavour break-up U/D you can see that the fc matters less than it did..make a tif file?

8. NEW OLD Include only variation of starting scale Q02: 2 → 6 GeV2 Has a small asymmetric effect on PDF ucertainties NEW/OLD look the same

9. NEW OLD Include only variation of starting scale Q02: 2 → 6 GeV2 Has a small asymmetric effect on PDF ucertainties NEW has slightly smaller model dependence than old- this is also as expected

10. NEW OLD Include only variation of minimum Q2 of fitted data Qmin2: 2.5 → 5 GeV2 Has an even smaller asymmetric effect on PDF ucertainties NEW/OLD look the same

11. NEW OLD Include only variation of minimum Q2 of fitted data Qmin2: 2.5 → 5 GeV2 Has an even smaller asymmetric effect on PDF uncertainties NEW/OLD look the same

12. But what about u,d,s,c?

13. BUT we never showed the world flvaour break-up OLD Now there really IS a new/old difference ..where does it come from?

14. NEW But look at flavour break-up OLD Old has just mb and mc…New haS JUST mb..beacuse it is no longer true that changing mc gives no model dependence!

15. NEW OLD Old has just mb and mc…New haS JUST mc.. it is no longer true that changing mc gives no model dependence! This makes sense. In dynamic generation the amount of charm does change with mc

16. NEW But look at flavour break-up OLD For the variation of fs, flavour break-up has not changed- good!

17. NEW But look at flavour break-up OLD NEW Fc used to make a difference because it was imposed. But with dynamic generation fc does Not change only the Ubar Dbar relative norm has changed

18. NEW OLD Change of Q0 used to affect the flavour break up a lot because fs and fc were not changed accordingly. Now they are changed it is not a big effect. I think this makes sense

19. NEW OLD The effect of the Q2 cut is small..can be seen in cbar

20. Change of alphas does affect cbar slightly– it is now dynamically generated from the gluon!