Event Mixing Method as applied on GEN EC smeared events
In all the events: E_gamma > 0.3 GeV; 8 < Theta < 45 ; Angle(e,gamma) > 12

POL2 Fit
Fig.1Inv. mass in z bins and pT2; background fitted with restricted POL2


z-bin: 1.45+/-0.04%, 0.31+/-0.02%, 0.18+/-0.01%, 1.21+/-0.03%, 0.15+/-0.01%, 0.26+/-0.01%, 0.26+/-0.01%, 1.33+/-0.02%, 0.02+/-0.00%;
average : 0.118 +/- 0.003 % pT2-bin: 1.33+/-0.03%, 0.45+/-0.01%, 0.03+/-0.00%, 0.19+/-0.01%, 0.84+/-0.02%, 0.20+/-0.01%, 0.32+/-0.01%, 0.21+/-0.01%, 0.40+/-0.01%;
average : 0.140 +/- 0.003 % q2-bins: 0.40+/-0.01%, 0.11+/-0.01%, 0.89+/-0.02%, 1.10+/-0.02%, 1.38+/-0.02%, 2.47+/-0.04%, average : 0.329 +/- 0.004 %
nu-bin: 0.03+/-0.00%, 0.49+/-0.01%, 0.70+/-0.02%, 0.82+/-0.02%, 0.35+/-0.02%, 0.72+/-0.03%, average : 0.061 +/- 0.002 %
N.B Here the error is stat. only, does not include error from the fit


Event Mixing
Fig.2a Here current and old photon are mixed into pi0 provided they belong to the same {Q2, Nu, z(pi0), pT2(pi0)} bins


Link to the shapes of the mixed background: Z , pT2
Fig.2b Here current and old photon are mixed in bins {Q2, Nu, z(pi0), pT2(pi0)} bins + photons are rotated


Link to the shapes of the mixed background: Z , pT2
Applying mixing method from Fig.2b in data and extracting corresponding back. provides following: fit of real events

Fig.2c Here mixing is done in bins + photons is rotated + mixed pi0 required to be in the same (z, pT2)bin


Link to the shapes of the mixed background: Z , pT2
Applying mixing method from Fig.2c to data and extracting corresponding back. provides following: fit of real events

Comparing Npi0 extracted with above method to the real number of pi0 generated in a given bin is gives following:
z: 1.35+/-0.12%, 1.23+/-0.08%, 1.34+/-0.05%, 1.03+/-0.04%, 1.35+/-0.03%, 1.31+/-0.02%, 0.73+/-0.01%, 0.08+/-0.00%, 0.00+/-0.00%, average : 0.023 +/- 0.001 %
pT2: 5.48+/-0.06%, 3.69+/-0.04%, 1.55+/-0.03%, 0.36+/-0.03%, 0.52+/-0.02%, 0.04+/-0.02%, 0.03+/-0.01%, 0.02+/-0.00%, 0.34+/-0.00%, average : 0.302 +/- 0.001 %
Q2: 0.83+/-0.02%, 0.96+/-0.02%, 1.80+/-0.02%, 1.96+/-0.02%, 2.19+/-0.02%, 1.58+/-0.03%, average : 1.450 +/- 0.008 %
Nu: 0.77+/-0.01%, 1.58+/-0.02%, 1.65+/-0.02%, 1.66+/-0.03%, 1.63+/-0.03%, 0.43+/-0.04%, average : 1.152 +/- 0.008 %


Selected bin (Q2,nu,z, pT2) = (0,2,0,...)
Fig.3a Slice in (0,2,0, pT2) bin from 4D invariant mass of RECONSTRUCTED MC (went throught GSIM)
Top panel - inv.mass fitted with POl2; Bottom - inv.mass fitted with binned+rotted mixed background.



Fig.3b Slice in the same bin from GENERATED MC. Top - fitted with POl2; Middle -with binned+rotated mixed bakc;
Bottom -same as middle+ pi0 mixed should be in the same bin as original pi0.





Fig.2c