Here I look at comparisons between particle jets and detector jets ...

Now that we are starting to see good agreement between data and simulation (see here for example), I want to start systematically looking at how jet properties change as they move into the endcap by comparing particle level jets to detector level jets. The ultimate goal is to develop a method to quantify and possibly correct for the loss in detected jet pt due to the falloff in tracking as jets move into the endcap.

When making the detector jet / particle jet comparisons below, I first select my dijet candidate from the detector jet branch: I pick the two jets with the highest pt, require at least one to point to a fired trigger patch, and require that they be back to back in phi. Then for each jet in the dijet, I find the particle level jet which is closest in eta-phi space, ie I find the particle level jet for which the quantity Sqrt{(etaDet-etaPart)^2 + (phiDet-phiDet)^2} is smallest. I also require that this quantity be less than 0.4 .

Figure 1: These figures show the pt, eta, detEta, and phi spectra for detector jets (blue) and particle jets (red). The top plots show the Hi jets and the bottom plots show the Lo jets.

Figure 2: This figure compares the pt of detector level jets to the pt of the matched particle level jets. The top left pannel shows detector - particle jet pt and the top right pannel shows detector/particle jet pt. In the top pannels, the black curve is for the full eta range, the red curve is for jets with detEta between -0.7 and 0.0, the blue cureve is for jets with detEta between 0.0 and 0.5, the light blue curve is for jets with detEta between 0.5 and 1.0, and the green curve is for jets with detEta between 1.0 and 1.7. The bottom pannels show detector - particle pt on the left and detector/particle pt on the right vs the detector eta of the jet.

Figure 3: This figure shows the detector jet - particle jet pt vs the detector jet pt. Each pannel shows a specific eta range, starting with top left: full eta, -0.7 - 0.0, 0.0 - 0.5, 0.5 - 1.0, 1.0 - 1.7 .

Figure 4: Same as figure 3 but now the detector jet / particle jet pt ratio is shown on the Y-axis.

Figure 5: This figure shows the particle jet pt vs the detector jet pt. Again, the ordering of the pannels is the same as in figures 3 and 4.

For the figures below, I make comparisons between the pts of the two jets in the dijet at both detector level and particle level. I first look at Barrel - Barrel jets to get a baseline of what things should look like with good tracking and then I look at Endcap - Barrel comparisons.

Figure 6: This figure shows the pt difference (Top) between the barrel jet with the higher eta and the barrel jet with the lower eta for Detector level jets (Black) and particle level jets (Red). The bottom pannel shows the ratio high eta pt / low eta pt.

 Figure 7: This figure shows the pt difference: endcap jet pt - barrel jet pt. The top left plot shows this difference for the detector level jets (Black) and the particle level jets (Red). The top right plot shows this difference for the detector level jets as a function of the detector level jet detEta of the endcap jet. The bottom plot shows the same for the particle level jet.

Figure 8: This is the same as figure 6 except I now show the endcap jet pt to barrel jet pt ratio.

Figure 9: This figure is a 2-D profile plot. The X Axis is the eta of the detector level jet with the higher eta and the Y Axis is the eta of the detector level jet with the lower eta. The Z axis shows the average value of the ratio of the high eta jet pt to the low eta jet pt. The top pannels show this ratio for detector level jets and the bottom pannels show this ratio for the particle level jets. Note: for the particle level plots, the eta-eta position is still given by the detector level jet.