https://doi.org/10.1140/epja/i2009-10877-3
Regular Article - Experimental Physics
On the production of 
pairs in pp collisions at 0.8 GeV
1
Ruhr-Universität Bochum, Bochum, Germany
2
Technische Universität Dresden, Dresden, Germany
3
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
4
Forschungszentrum Jülich, Jülich, Germany
5
Forschungszentrum Rossendorf, Rossendorf, Germany
6
Physikalisches Institut der Universität Tübingen, Tübingen, Germany
7
Sezione di Torino, University of Torino and INFN, Torino, Italy
8
Atomic Energy Authority NRC, Cairo, Egypt
9
Soltan Institute for Nuclear Studies, Warsaw, Poland
10
Rheinische Friedrich-Wilhelms-Universität, Friedrich, Bonn
* e-mail: clement@pit.physik.uni-tuebingen.de
Received:
18
June
2009
Revised:
11
September
2009
Accepted:
15
September
2009
Published online:
4
October
2009
Data accumulated recently for the exclusive measurement of the pp
pp
reaction at a beam energy of 0.793GeV using the COSY-TOF spectrometer have been analyzed with respect to possible events from the pp
nn
reaction channel. The latter is expected to be the only 
production channel, which contains no major contributions from resonance excitation close to threshold and hence should be a good testing ground for chiral dynamics in the
production process. No single event has been found, which meets all conditions for being a candidate for the pp
nn
reaction. This gives an upper limit for the cross-section of 0.16μb (90% C.L.), which is more than an order of magnitude smaller than the cross-sections of the other two-pion production channels at the same incident energy.
PACS: 13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) – / 14.20.Gk Baryon resonances with S = 0 – / 25.10.+s Nuclear reactions involving few-nucleon systems – / 25.40.Ep Inelastic proton scattering –
© SIF, Springer-Verlag Berlin Heidelberg, 2009
