Eur. Phys. J. A (2006) 28: 115-124
https://doi.org/10.1140/epja/i2006-10025-9

Hadron Physics

Upper limits on resonance contributions to proton-proton elastic scattering in the c.m. mass range 2.05-2.85 GeV/ c²

¹ Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115, Bonn, Germany
² Institut für Experimentalphysik, Universität Hamburg, D-22761, Hamburg, Germany
³ Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany

^* e-mail: fh@hiskp.uni-bonn.de

Received: 10 March 2006
Accepted: 21 April 2006
Published online: 16 May 2006

Abstract

Recently published excitation functions in proton-proton (pp) elastic scattering observables in the laboratory energy range 0.5-2.5GeV provide an excellent data base to establish firm upper limits on the elasticities η_el = Γ_el/Γ_tot of possible isovector resonant contributions to the nucleon-nucleon (NN) system. Such contributions have been predicted to arise from dibaryonic states, with c.m. masses between 2.1-2.9GeV/c², but have not been confirmed experimentally. A method to determine quantitatively the maximum value of η_el compatible with experimental data is presented. We use energy-dependent phase shift fits to the pp data base to model the non-resonant interaction. Based upon the differential cross-section data measured by the EDDA Collaboration an unbiased statistical test is constructed to obtain upper limits on η_el, that exclude larger values with a 99% confidence level. Results in the c.m. mass range 2.05-2.85GeV/c² and total widths of 10-100MeV/c² in the partial waves ¹ S ₀, ¹ D ₂, ³ P ₀, ³ P ₁, and ³ F ₃ are presented and discussed.