Continuing my hi pt track correction studies ...

A previous study has found that a 'good' RFF spectra for sector 20 can be transformed into a 'bad' FF spectra by altering the track sagitta by an amount determined by randomly choosing a value according to a gausian distribution. The study found that the gausian parameters which described the positive and negative corrections where: Mean = 0.66 and Sigma = 0.35.

With the gausian sagitta shift seemingly doing a good job at explaining the negative and positive FF track pt spectra seen in sector 20, the last bit of the puzzle is how to explain the difference in track distortion seen in the high pt jet and low pt jet. So far, I have been applying the gausian corrections to the combined high and low jet track pt spectrum, but if you compare the RFF and FF track pt spectra for the high and low jet seperately, you see that the FF tracks from the high jet are distorted much more than the FF tracks from the low jet. See Figure 1 on this page. My model will need to be able to reproduce this feature if I am to trust it as a representation of what is acutally happening in sector 20 during the FF part of the run.

My hypothesis is that the differences between the high and low pt jets is created by the jet finder. The most distorted tracks are grouped into the high pt jets leaving the least distorted tracks for the low pt jet. To test this idea, I have modified the jet finder to use track pts that have been distorted by the gausian sagitta shift explained in earlier posts. In addition to the distorted pt that was used in the jet finding, I have saved the original pt so that comparisons between the origninal and modified track pt spectra can be made.

Figure 1: This figure compares the modified and unmodified track pt spectra obtained by running the modified track pts through the jet finder. The top left pannel shows the modified (red) and unmodified (blue) spectra for the high pt jet. the top right pannel shows the same spectra for the low pt jet. The bottom two pannels show the modified vs unmodified scatter plots. All spectra are for the positive charge sign tracks.

Figure 2: This figure is the same as Figure 1 but for the negative charge sign tracks.

Figure 3: This figure compares the track length from the TPC which is used to correct the track pt in this analysis and the track length from the projection of the track into the calorimeters which was used to correct the track pt in the previous analyses.