In a previous blog entry I discussed revisiting the trigger definitions for analysis of the 2011 JP-triggers. The confounding issue was the behavior of AJP which exhibited no sign of a trigger "turn-on." Zilong looked into this as well and found that by completely relaxing the p_T threshold, it appears the AJP turn-on is evident. My previous update set a minimum of 7.1 GeV, corresponding to the lowest allowed p_T for a JP0 trigger. His analysis did not include the trigger simulator, since his sample of jet trees were made before the update. Here, I examine lowering the thresholds while also including the trigger simulator in the trigger definitions.

Figure 1

In Fig. 1 I examine the trigger definitions for the "standard" definitions compared to removing the p_T requirement. Now, the p_T threshold is relaxed all the way to 5 GeV. Indeed, now, there does appear to be a slight rise in the AJP spectra, peaking around 8-9 GeV. This was not evident in previous plots which cut off at 7.1 GeV, where the "rise" was disguised as statistical fluctuation.

Figure 2

In Fig. 2, I compare AJP to JP2 for the relaxed definition. The turn-on is quite clear when one singles-out the highest-p_T jet. Around 15 GeV, the AJP distributions merge. My guess is that there is splitting related to the AJP trigger as well as the jet algorithm that play a role in the low-threshold behavior. Examination of simulation is, now, quite important.