Pions in Jets study

Jet Pion Study


In making the below plots, I employed the Spin Analysis Trees recently put together.  I used all of the jets available, in all the jet triggers, assuming that the jets in the analysis tree are "physics" jets.  I used pions from the L2-gamma and L2-gamma-test triggers.  I used a run if it passed both my pion QA and Murad/Steve's Jet QA.  That is, I used only those runs that were in both my golden run list and Jim Sowinski's golden run list.

First I look for any event with a pion found with -0.3 < Pion Eta < 0.3.  I then loop over every jet in that event looking for any jet that is less then 0.7 away in Sqrt((delta Eta)2 + (delta phi)2).  I look in such a limited Eta range for the pion so as to avoid any edge effects.  I then make a histogram of the ratio of pion Pt to Jet Pt and take the mean value of that histogram.  This mean value is plotted below.

Currently this includes pions only from BBC timebinds 7,8, and 9.  But I will soon add timebin 6 as well.


The above plot shows the ratio of Pion Pt to Jet Pt as a function of the Pion's Pt.  It looks like as Pt gets higher and higher the ratio tends towards a fixed value between 75% and 80%

This histogram shows the distance in eta and phi between pion and associated jets.  As you can see the RMS in the Eta-plane (x axis) is 0.064 and the RMS in the Phi-plane (y axis) is 0.055, which corresponds to the values from run 5.