https://doi.org/10.1140/epja/i2010-11033-x
Regular Article - Theoretical Physics
On the background in the 
p 
(
)p reaction and mixed event simulation
1
Institut für Theoretische Physik, Universität Giessen, D-35392, Giessen, Germany
2
Departamento de Fısica Fundamental e IUFFyM, Universidad de Salamanca, E-37008, Salamanca, Spain
3
Departamento de Fısica Teórica e IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigación de Paterna, Aptd. 22085, E-46071, Valencia, Spain
* e-mail: murat.kaskulov@theo.physik.uni-giessen.de
Received:
5
July
2010
Accepted:
31
August
2010
Published online:
3
October
2010
In this paper we evaluate sources of background of the 
reaction, with the detected through its 
decay channel, to compare with the experiment carried out at ELSA. We find background from 
followed by decay of a 
into two , recombining one and one , and from the 
reaction with subsequent decay of the 
into two photons. This background accounts for the data at invariant masses beyond 700MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once this is done, we perform an event mixing simulation to reproduce the calculated background and we find that the method provides a good description of the background. A closer look reveals this is accidental. We show that the mixed event generated background in the region of the mass and beyond is completely tied to the events at low invariant masses where the 
distribution is much larger. This has as a consequence that the mixed event method produces the same background at high invariant masses independently of the actual background in that region, as a consequence of which, the method is unsuited to give the background at energies around the peak of the and beyond.
© SIF, Springer-Verlag Berlin Heidelberg, 2010
