# Pythia Tunes and PDFs: Effects on Cross Section

Updated on Thu, 2015-11-05 12:01. Originally created by pagebs on 2015-10-07 13:15.

A look at how different pythia tunes, PDF sets, and intrinsic kT settings could affect the dijet cross section ...

Figure 1: The correction factor for several different simulation settings. The top panel shows the correction factor used to correct theory to the particle level cross section with jet mass included and is the ratio of the full particle level yield over the no mass parton level yield. The bottom panel is the same for the cross section without the jet mass included and is the ratio of the no mass particle level yield over the no mass parton level yield. Note that the black and green curves were created with the same tune settings but with different PYTHIA versions (black = 6.4.26 and green = 6.4.28) and different statistics, they agree within error. The red curve (TuneA) was also created using PYTHIA version 6.4.26.

Figure 2: The ratio of the data and theory cross sections with and without mass, and with correction factors applied to the theory. The correction factors were calculated using the native embedding sample (Perugia0, Pythia 6.4.26). Theory from CTEQ6M. NOTE: for the massless cross section, the correction factor is taken as the particle/parton yield where both are taken with the no jet mass dijet mass formula.

Figure 3: Same as figure 2 but now correction factors are calculated from TuneA simulation.

Figure 4: Same as figure 2 but now correction factors are calculated from Perugia0 (using Pythia 6.4.28) with kT adjusted to 0.5

Figure 5: Same as figure 2 but now correction factors are calculated from Perugia0 (using Pythia 6.4.28) with the CTEQ6 PDF set (pdf = 10000 in LHAPDF 6.1.5)

Figure 1: The correction factor for several different simulation settings. The top panel shows the correction factor used to correct theory to the particle level cross section with jet mass included and is the ratio of the full particle level yield over the no mass parton level yield. The bottom panel is the same for the cross section without the jet mass included and is the ratio of the no mass particle level yield over the no mass parton level yield. Note that the black and green curves were created with the same tune settings but with different PYTHIA versions (black = 6.4.26 and green = 6.4.28) and different statistics, they agree within error. The red curve (TuneA) was also created using PYTHIA version 6.4.26.

Figure 2: The ratio of the data and theory cross sections with and without mass, and with correction factors applied to the theory. The correction factors were calculated using the native embedding sample (Perugia0, Pythia 6.4.26). Theory from CTEQ6M. NOTE: for the massless cross section, the correction factor is taken as the particle/parton yield where both are taken with the no jet mass dijet mass formula.

Figure 3: Same as figure 2 but now correction factors are calculated from TuneA simulation.

Figure 4: Same as figure 2 but now correction factors are calculated from Perugia0 (using Pythia 6.4.28) with kT adjusted to 0.5

Figure 5: Same as figure 2 but now correction factors are calculated from Perugia0 (using Pythia 6.4.28) with the CTEQ6 PDF set (pdf = 10000 in LHAPDF 6.1.5)

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