The current objective is to make an embedded and filtered simulation request needed for the pp 500GeV dijet cross-section measurment. Progress has been made to determine the bias of the pythia level dijet filter and trigger filter. We now examine the effects embedding zerobias events into simulation has on the distributions of several observables. I do this by comparing the output of the bfc macros implemented for the pp 200GeV Dijet simulation request (see first attachment) and pp 500 W Analysis embedded simulation request (see second macro). Note that for the embedded simulation 1242 events were thrown and in the simulation-only case 1200 events were thrown.

 

First, we look at jet distributions:

 

Fig 1: Jet pT spectrum for simulation (top) and embedded simulation (bottom).

 

Fig 2: Jet phi distribution for simulation (top) and embedded simulation (bottom)

 

Fig 3: Jet Eta spectrum of simulation (top) and embedded simulation (bottom)

 

Now we examine the tracks within the jets:

 

Fig 4: Track pT spectrum for simulation (top) and embedded simulation (bottom).

 

 

 

Fig 5: Track phi spectrum for simulation (top) and embedded simulation (bottom).

Fig 6: Track eta spectrum for simulation (top) and embedded simulation (bottom).

 

Now to examine the Tower in the jet distributions:

 

Fig 7: Tower E spectrum for simulation (top) and embedded simulation (bottom).

Fig 8: Tower phi spectrum for simulation (top) and embedded simulation (bottom).

 

Fig 9: Tower eta spectrum for simulation (top) and embedded simulation (bottom).

 

The Embedding process seems to be working properly and all distributions appear to behave as expected. Since we have examined the performance of the dijet pythia filter and trigger filter on straight simulation (see link), we now want to examine the performance of the filters using the embedded scenario. We examined the pT bin with the largest filter bias (pT bin 25-35 GeV) from the previous study. The results can be seen in the following table:

 

Table 1: Performance of the Dijet Filter Test

pT Bin	Events Thrown	Events Passing Pythia Filter	Events Passing Pythia Filter & Trigger	Events Failing Pythia Filter but had dijets after BFC	Events Failing Pythia Filter but had dijets after BFC & Passed the Trigger	Events Passing Trigger Filter	Events needed for 1pb-1
25-35	11157	6636	5154	39	24	7756

 

CONCLUSIONS:  

As expected embeddeding zero bias events in simulation decreases the average jet pT and jet track pT.  In spite of slightly more events being thrown, it can been seen from the plots above that number of jets and tracks within the jets are in fact less in the embedded scenario. However, the number of towers within a jet slightly increase. We suspect this to be the result of split/merge effects. The distribution of zero bias events causes low pT jets to be split instead of merged and therefore not satisfy the 5GeV jet pT threshold. Ultimately, causing the number of jets to decrease.