Difference in StJetMaker2012 vs. StJetMaker2015

- Response to Carl and Zilong's comments in jet meeting at Jan. 8:
   source of minor differences in barrel eta/phu distribution

- A couple of quick QA performed:
  a. Restrict jet reconstruction eta from [-1, 5] -> [-1, 1]
  b. a. + comments out the part "No TPC vertex found"
      (* major change in StJetMaker2015: uses all possible vertex if no TPC vertex is found)

- Results:eta/phi distribution, StJetMaker2012 (left, black or red) vs. StJetMaker2015 (right, blue or magenta)
  * I draw distributions from tree directly - official library was not necessary

- Conclusion: minor discrepancy originated from newly updated part (case for no TPC vertex found).
  Two libraries show exact match for item b.


   1. eta, item a, 2012 vs. 2015

    2. eta, item b, 2012 vs. 2015


   3. phi, item a, 2012 vs. 2015

   4. phi, item b, 2012 vs. 2015