Eur. Phys. J. A (2009) 42: 159-161
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

Abstract

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.