Placeholder page showing plots as I develop a method of correcting the pt of jets in the endcap ...

Currently, I am testing two methods for correcting the jet pt in the endcap region. The first method uses a fit to the average value of the ratio of Detector Jet Pt to Particle Jet Pt as a function of eta. I have created plots like this for 6 different pt ranges (See Fig 2) and fit an appropriate region. The corrected pt is found by dividing the measured pt by the factor given by the appropriate fit. The second method uses a fit to the average value of a Particle Jet Pt to Detector Jet Pt scatter plot. These plots are divided into 6 different eta ranges (See Fig 3) and different fits are made for each region. For this method, the corrected pt is read off directly from the fit.

Figure 1: This shows the detector / particle jet pt ratio as a function of detector jet det eta for all pt.

Figure 2: This shows the detector / particle jet pt ratio as a function of detector jet det eta for different pt bins.

The plots and fits shown in Figure 2 are used in the 'Method 1' correction scheme. The measured jet pt is used to determine which fit function should be used. Then the correction ratio is found by plugging the measured jet detEta into the fit function. Finally, the corrected jet pt is found by dividing the measured jet pt by the correction ratio. Note that correction factors for pt's between 5 and 20 GeV are applied for detEta's of 0.5 - 1.7. For pt's between 20 and 25 GeV, corrections are only applied for detEta's between 1.0 and 1.7 and for pt's above 25 GeV, no correction factors are applied.

Figure 3: This shows the particle vs detector jet pt for different eta bins.

Figure 3 shows the plots and fits used in the 'Method 2' correction scheme. Here it is the detEta of the measured jet that is used to determine which fit function is used. The corrected pt is just found by plugging the measured pt into the fit function. Note that for detEta between 0.5 and 1.0, corrections are applied for measured jet pt's below 35 GeV and for detEta between 1.0 and 1.7, corrections are applied for measured jet pt's below 25 GeV.

Figure 4: This figure shows how the two correction methods modify the jet pt in pt-eta space. The top two plots show Abs(Corrected Pt - Input Pt) for different values of pt and detector eta for the two methods described above. The white regions represent areas where no correction was applied so there is no difference between input and corrected pt. The bottom left plot shows Abs(Method 1 Corrected Pt - Method 2 Corrected Pt), in essence showing how much the corrected jet pt differs as computed using the two methods. The bottom three plots display the same info in 3-D.

The final step in testing these two correction methods is to rerun the simulation while applying the appropriate correction factors. The results are shown in the following two figures.

Figure 5: This figure shows the detector / particle jet pt ratio vs detector eta. The top left pannel shows the ratio for the uncorrected jet pts. The top right pannel shows the ratio using the detector pt corrected using Method 1 described above. The bottom left pannel shows the ratio using the detector pt corrected using Method 2 described above.

Figure 6: This figure shows the particle jet pt vs the detector jet pt correlation. The top left pannel shows the ratio for the uncorrected jet pts. The top right pannel shows the ratio using the detector pt corrected using Method 1 described above. The bottom left pannel shows the ratio using the detector pt corrected using Method 2 described above.

Figure 7: This is the same as figure 2 except that I now fit with a modified fermi function. The form is: A+(1-A)/(Exp[(x-B)/C]+1). The vertical error bars on the points are now 1/Sqrt(Sum W_i) instead of the RMS of the distribution.