Electron to Positron ratio as a function of P_T, for 2005 and 2006. Ratio shown for inclusive and photonic electrons, where a photonic electron (positron) is defined as an inclusive electron (positron) that can be paired with another positron (electron) and create a pair that satisfies the photonic electron id cuts.

January 16 update:

Ratio calculated separately for east and west halves of the TPC for 2006. 2005 data only uses the west half.

East electrons (positrons) are defined as those with event primary z-vertex, PVertexZ < 0 and track Eta < 0.

West electrons (positrons) are defined as those with event primary z-vertex, PVertexZ > 0 and track Eta > 0.

The ratio is fitted using the function:

f(P_T) = [ (2.67+P_T+A*P_T²) / (2.67+P_T-A*P_T²) ]^11.4

where A is the fit parameter (p0 in fit panels).

2005:

Inclusive electron / positron ratio vs. P_T

From the following P_T distribution: electron positron

Photonic electron / positron ratio vs. P_T

From the following P_T distribution: electron positron

2006:

Inclusive electron / positron ratio vs. P_T

From the following P_T distribution: west electron west positron east electron east positron

Photonic electron / positron ratio vs. P_T

From the following P_T distribution: west electron west positron east electron east positron