Update 08.13.2018 -- Run 9 embedding: Updated Jet Matching Efficiency and Jet Energy Resolution (R = 0.2, 0.3, 0.4, and 0.5)
The last time I calculated the JER for R = 0.4, I noticed the matching efficiency was abnormally low. In the post below, I checked if it was due to my matching algorithm. It wasn't.
It turned out to be substantially more mundane: I used the wrong area cut. For R = 0.4, the area cut we've been using is 'Ajet > 0.35', but I used 'Ajet > 0.5' in the JER calculation. The plots below show the distributions of the jet pT (before rho subtraction) vs. the jet area.
The dotted lines indicate the usual area cuts. Here are the percentages of jets lying above the area cuts above:
| Rjet | Acut | Integral (all) | Integral (cut) | percentage |
| 0.2 | 0.05 | 4759750 | 4735625 | 99.5 |
| 0.3 | 0.2 | 4131714 | 3674714 | 88.9 |
| 0.4 | 0.35 | 3098714 | 2716000 | 87.6 |
| 0.4 | 0.5 | 3098714 | 894429 | 28.9 |
| 0.5 | 0.65 | 3156600 | 2234600 | 70.8 |
And just for clarification, the above distributions are integrated over delta-phi. Using the correct (Ajet > 0.35) cut, the jet matching efficiencies look like so:
So mystery solved! And with the correct cut, the R = 0.4 JER looks like so:
And, of course, the R = 0.2, 0.3, and 0.5 JER can be found in the post below.
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