PPT here

Bob talked about Jet triggers used by D0 during Run I, with an emphasis on those used to do precision QCD analyses, like the inclusive jet cross section.  He talked about the difficulty of getting precision numbers for jet efficiencices, especially in the turn-on part of the jet Pt spectra.   Especially, jets that pass the trigger in the "turn-on" region of the Pt spectra tend to be narrower than average jets, and this is difficult to model.  He said that using Monte Carlo to get a precision efficiency was difficult because it was difficult to get a good model for the trigger pick-off part of the electronics.  The resolution, timing etc depended on cable lengths and other difficult to model effects.  For detailed information, please see his slides.

 

postscript here

Ed has been studing the effect of trigger-level phi segmentation of the HF on the L1 MET trigger.  He is studying jets from WW fusion production of a Higgs boson.   These events contain forward tagging jets, in the eta region between eta =2 and eta =5.  The HF starts at around eta of 3.4.  He considers 10, 20, and 30 degree segmentation.  He finds that the Jet ET, eta, phi, and MET at the reconstructed level looks similar for all 3 segmentations.  His preliminary conclusion is that 30 degree segmentation is okay.  However, he is going to make turn-on curves for the various segmentations, to make a more careful check.

 

 

PDF here

Sridhara presented studies comparing the current L1 jet trigger with a 3x3 sliding window jet trigger.  He finds that the a 3x3 algorithm whose 95% efficiency point is at 125 GeV gives the same rate as the current algorithm does when its set so thats in 95% efficiency point is 150 GeV.    He finds that the rms on offline-l1 goes from 19 GeV to 17 GeV for jets in his sample.  The offset goes from 45 GeV to 25 GeV.   In last weeks talk, Sarah Eno showed plots from a signal sample (1 TeV zprime) that shows the resolution changing from   16% with an offset of .71 to 6.6% with an offset of .91.  It is not clear whether this difference is due to the different type of event (QCD versus signal) or because Sarah required the jets have eta < 1.5., or because she was using Emilio's code as her base.