Looking at the systematics on the underlying event and hadronization correction to the theoretical cross section ...

Figure 1: Effect of changing the Q^2 scale by 2.0 and 0.5 times on the underlying event and hadronization correction. The upper panel shows the particle over no mass parton ratio which is used to correct theory for comparison to the full mass particle level cross section, and the bottom panel shows the no mass particle over no mass parton dijet yield ratio which is used for the no mass particle level cross section. The black and green curves show both use the same tune, but the black is the standard embedding sample created with Pythia 6.4.26 and the green curve is the sample created with Pythia 6.4.28, they are consistent.

 

Figure 2: The underlying event and hadronization correction for different error sets from the CTEQ6 PDF set. The upper panel shows the particle over no mass parton ratio which is used to correct theory for comparison to the full mass particle level cross section, and the bottom panel shows the no mass particle over no mass parton dijet yield ratio which is used for the no mass particle level cross section. The blue curve is the value from the standard embedding sample while the red curve is from Pythia 6.4.28, Perugia0 with the CTEQ6 central value PDF. The black curves are from 5 (1, 10, 20, 30, and 40) error sets associatied with the CTEQ6 set.