Investigate model uncertainties OLD/NEW

Investigate model uncertaintiesOLD/NEW

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

OLDNEW

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

OLDNEW

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

NEWOLD

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

NEWOLD

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!

NEWOLD

If you look at flavour break-up U/D you can see that the fc matters less than it did..make a tif file?

NEWOLD

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!

NEW

Include only variation of starting scale Q02: 2 → 6 GeV2

Has a small asymmetric effect on PDF ucertainties

NEW/OLD look the same

NEWOLD

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

NEWOLD

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

NEWOLD

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

NEWOLD

But what about u,d,s,c?

BUT we never showed the world flvaour break-up

Now there really IS a new/old difference ..where does it come from?

OLD

Old has just mb and mc…New haS JUST mb..beacuse it is no longer true that changing mc gives no model dependence!

But look at flavour break-upNEW

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

NEWOLD

But look at flavour break-up

For the variation of fs, flavour break-up has not changed- good!

NEWOLD

But look at flavour break-up

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

NEW

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

NEWOLD

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

NEWOLD

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