Systematic study of the pp -> pp omega reaction
Abstract
A systematic study of the production of omega-mesons in proton-proton-collisions was carried out in a kinematically complete experiment at three excess energies(epsilon= 92, 128, 173MeV). Both protons were detected using the large-acceptance COSY-TOF spectrometer at an external beam line at the Cooler Synchrotron COSY at Forschungszentrum J\"ulich. The total cross section, angular distributions of both omega-mesons and protons were measured and presented in various reference frames such as the overall CMS, helicity and Jackson frame. In addition, the orientation of the omega-spin and invariant mass spectra were determined. We observe omega-production to take place dominantly in Ss and Sp final states at epsilon = 92, 128 MeV and, additionally, in Sd at epsilon= 173 MeV. No obvious indication of resonant omega-production via N^*-resonances was found, as proton angular distributions are almost isotropic and invariant mass spectra are compatible with phase space distributions. A dominant role of ^3P_1 and ^1S_0 initial partial waves for omega-production was concluded from the orientation of the decay plane of the omega-meson. Although the Jackson angle distributions in the omega-p-Jackson frame are anisotropic we argue that this is not an indication of a resonance but rather a kinematical effect reflecting the anisotropy of the omega angular distribution. The helicity angle distribution in the omega-p-helicity frame shows an anisotropy which probably reflects effects of the omega angular momenta in the final state; this observable may be, in addition to the orientation of the omega decay plane, the most sensitive one to judge the validity of theoretical descriptions of the production process.
Keywords
Cite
@article{arxiv.1001.3043,
title = {Systematic study of the pp -> pp omega reaction},
author = {TOF Collaboration and M. Abdel-Bary and S. Abdel-Samad and K. -Th. Brinkmann and H. Clement and J. Dietrich and E. Doroshkevich and S. Dshemuchadse and K. Ehrhardt and A. Erhardt and W. Eyrich and A. Filippi and H. Freiesleben and M. Fritsch and W. Gast and A. Gillitzer and J. Gottwald and H. Jäger and B. Jakob and R. Jäkel and L. Karsch and K. Kilian and H. Koch and M. Krapp and J. Kreß and E. Kuhlmann and A. Lehmann and S. Marcello and S. Mauro and P. Michel and K. Möller and H. P. Morsch and L. Naumann and N. Paul and C. Pizzolotto and Ch. Plettner and S. Reimann and M. Richter and J. Ritman and E. Roderburg and A. Schamlott and P. Schönmeier and W. Schroeder and M. Schulte-Wissermann and T. Sefzick and M. Steinke and G. Y. Sun and A. Teufel and W. Ullrich and G. J. Wagner and M. Wagner and R. Wenzel and A. Wilms and P. Wintz and P. Wüstner and P. Zupranski},
journal= {arXiv preprint arXiv:1001.3043},
year = {2012}
}
Comments
17 pages, 16 figures, accepted for publication in EPJA