I would like to make here few points about our background in NOV02 experimantal and simulated data.
Presented below pictures are made for the full HARD CUTS analysis. And all cuts are already applied.
Background is calculated with the like-sign same event method.

background: PLUTO true and reconstructed vs. EXP

background: PLUTO and UrQMD reconstructed vs. EXP

Just for the comparison i have added also the background from the UrQMD, where we have not only the leptons
inside, but also hadrons. One can see from this, that indeed comparing PLUTO with UrQMD,
we have more background in case of the UrQMD

Since now for the simplicity I will concentrate only on the PLUTO simulation.
SIMULATION is done with the standard PLUTO macro, including gamma conversion with the external macro.
Then the events are filtered with the acceptance matrix. There is no full analysis involved into this.

Opening angle distribution for the signal (NO PAIR CUTs)

Table below shows the reduction [%] of the true signal for the cocktail components.

SOURCE	REDUCTION [%]
pi0	74
gamma	97
eta	65
delta	68
omega Dalitz	63
omega Direct	-
rho	-

Opening angle distribution for the simulated signal (NO PAIR CUTs)

Looking into the background (also correlated one) opening angle will not removed a lot of it.
Please keep in mind that this is TRUE background.

By comparing the TRUE and RECONSTRUCTED background in simulation, we can see that we are close to 100 % agremment,
appart of the pi0 region. And this would means that the additional yield in the experimental background comes from hadrons most probably.

-- GosiaSudol - 27 Mar 2007