A few weeks back I spoke about investigating a different background method. This was described in Background investigation. Breifly, I was paring across events rather then using the like-sign pairs in an event to make background. This means that any correlations between the paired track within an event are removed, however, the method of normalisation is not a funcition of 2srt(N++*N--) as usual but rather uncertain.
To comapre the background fairly the like-sign pairs have been normalised with the same method as the cross event paring method
Here, we see like-sign paring, the background has been normalised by taking the integral outside the peak region, 6-8 and 10-12 Gev. This is an estimate and may be cutting into the signal peak. This has to be looked at in more detail
And for cross event paring with the same normalisation
The effect of the preshower was not great with the PID cuts applied, similar to what we have seen before with the like sign background
