Investigate model uncertainties OLD/NEW But what about u,d,s,c?

Now there really IS a big new/old difference..where does it come from in detail? (don’t bother looking at the blue lines- that’s another story) OLDNEW

For the variation of fs, new/old look pretty much the same- as they should NEW OLD

Old had mb and mc -neither made any difference New has JUST mb.. it is no longer true that changing mc gives no model dependence! For variation of mb NEW/OLD are the same NEW OLD Variation of mb

Variation of the Q2 cut NEW/OLD similar- slight difference in cbar NEW OLD Variation of Q2min

Old had 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 NEW OLD

Varaition of fc used to make a difference because it was imposed. But with dynamic generation fc does NOT change the amount of cbar Only the Ubar Dbar relative norm has changed – we CAN’t Agree on this unless we both do it dynamically NEW OLD Variation of fc

Change of Q20 used to affect the flavour break up a lot because fs and fc were not changed accordingly. Now that fs anf fc are changed with Q20, the change of Q20 itself is not a big effect. NEW OLD Change of Q20

LEFT 6 model variations RIGHT 6 model variations PLUS alphas variation Change of alphas does affect cbar slightly– because it is now dynamically generated from the gluon!

Comparsion of NEW standard to other parametrisations – H1 and humpy are not dynamic- this seems to affect high-x cbar most.