Two of the cuts that significantly reduced the number of electrons available for this analysis is the event primary vertex-z and track-η cuts. The values currently used were mainly inherited from previous analyses. Since this analysis is limited by statistics, it would be a good idea to confirm whether the strict cuts on these two values are really necessary. Following this brief study, it was decided to loosen the cuts.

Changing these two cuts from the previous to the newer cuts approximately doubles the number of electrons available for asymmetry analysis.

Primary Vertex Z

New cut: -70cm < V_Z < 40cm

Previous cut: +/- 35 cm, supposedly to avoid increased photonic electrons from SVT support structure

This cut seems unnecessarily strict, and results in too large of a cut in statistics. So to investigate where exactly this increase in photonic electron yield happens, we look at the ratio of inclusive / photonic electron yield as a function of Vertex-Z. Shown below is the ratio for tracks with TPC-eta range of (0.4,0.8). Ratio for additional eta ranges attached.

There doesn't seem to be a significant decrease in the ratio beyond 35 cm.

However, some sort of cut on Vertex-Z is probably needed, so we look at the raw electron yield to determine this cut.

 To preserve as much statistics as possible, a cut of (-70cm,40cm) seems reasonable.

Track-η

New cut: |Point-η| < 0.8

Previous cut: |Track-η| < 0.7

 As done for to study the Vertex-Z cut, we also look at the inclusive / photonic electron ratio as a function of Track-η. The black dots is for full EMC acceptance, i.e. Point-η (0,1), red dots for Point-η (0,0.9) and blue dots for Point-η (0,0.8). Using the full west BEMC, the ratio increases at higher Track-η, likely due to lowered efficiency in identifying photonic electrons (to be confirmed). Cutting out the edge of the BEMC seems to level out the ratio at higher Track-η.