Strict Eta Cut Reproduction

 Comparison of dijet quantities using the two different eta cut criteria ...


Originally the dijet selection process was to find the two highest pt jets over the eta range -0.8 to 1.8 and then apply other cuts such as asymmetric pt, opening angle, and the eta cuts to look at mid-rapidity. The GPC thought that it may be better to look for the two highest pt jets in the region -0.8 to 0.8 and take those jets as the dijet candidate, disregarding jets outside the eta range which will be analyzed. This page will document the differences in these two approaches.

Throughout this page, loose eta cut refers to the original scheme in which the two highest jets in the full eta range (-0.8 to 1.8) were taken as the dijet candidate. Strict eta cut refers to the new scheme where the two highest pt jets in the range -0.8 to 0.8 are taken as the dijet candidate.

Plots below are for data:


Figure 1: Number of dijets found per run. Strict eta cut (blue) loose eta cut (red). L2JetHigh on left and JP1 on right. 
 


Figure 2: Jet pt spectra for the strict (blue) and loose (red) eta cuts. L2JetHigh on left and JP1 on right.


Figure 3: Jet eta spectra for the strict (blue) and loose (red) eta cuts. L2JetHigh on left and JP1 on right.


Figure 4: Jet phi spectra for the strict (blue) and loose (red) phi cuts. L2JetHigh on left and JP1 on right.


Figure 5: Full range dijet delta phi 
for the strict (blue) and loose (red) phi cuts. L2JetHigh on left and JP1 on right.


Figure 6: Limited
 range dijet delta phi for the strict (blue) and loose (red) phi cuts. L2JetHigh on left and JP1 on right.


Figure 7: Dijet mass for the strict (blue) and loose (red) phi cuts. L2JetHigh on left and JP1 on right.




Here I look at the Data Asymmetry (ALL)


Figure 8: Uncorrected dijet ALL for the strict (blue) and loose (red) eta cuts. Top plot is full topology, middle is EEWW, and bottom is EW.





 
 
It is seen that the fourth bin of the EEWW topology shows a rather large difference between the strict and loose cases. Because the asymmetries are small, the absolute difference is almost imperceptible on the asymmetry plot but the ratio is on the order of 20% while all other differences are below the 10% level. As a check I looked at the raw number asymmetry, the asymmetry with polarization terms removed, and the asymmetry with the relative luminosity terms removed.
 
 
 
Figure 9: Same as figure 8, but I have removed the relative luminosity term from the asymmetry expression. 
 






Figure 10: A_LL corrected to parton level with the trigger and reconstruction bias included. The loose cut points are in red and the strict cut points are in blue. The top panel is the full topology, the middle is EEWW, and the bottom is EW. Note: the vertical error bars are statistical only and the horizontal error bars are dummy, just meant to help see shifts in mass. No systematic errors have been included.




 
 
This text file shows the shifted parton mass values and trigger and reconstruction bias corrected A_LL values for the strict and loose points along with differences and ratios.