Eur. Phys. J. A 17, 245-267 (2003)
DOI: 10.1140/epja/i2002-10145-2

Experimental evidence for narrow baryons in the mass range  GeV

B. Tatischeff ¹, J. Yonnet¹, M. Boivin², M.P. Comets¹, P. Courtat¹, R. Gacougnolle¹, Y. Le Bornec¹, E. Loireleux¹, M. MacCormick¹, F. Reide¹ and N. Willis<sup>1

1</sup>  Institut de Physique Nucléaire, CNRS/IN2P3, F-91406 Orsay Cedex, France
²  Laboratoire National Saturne, CEA/DSM CNRS/IN2P3, F-91191 Gif-sur-Yvette Cedex, France

tati@ipno.in2p3.fr

(Received: 3 July 2002 / Revised version: 28 January 2003 / Published online: 5 June 2003)

Abstract
The reaction was studied at different incident energies around  GeV. Narrow baryonic structures were observed in the missing mass and in the invariant mass . The masses of these structures are 1004, 1044, 1094, 1136, 1173, 1249, 1277, and 1384 MeV (and possibly 1339 MeV). Some of them were also observed at the same masses in the missing-mass spectra of the dp   ppX reaction although with a weaker signature. Many checks were performed to make sure that these structures were not produced by experimental artifacts. Several narrow small-amplitude peaks, were also extracted using already published photonucleon cross-sections. The small widths of all these results, and the stability of the observed structures, regardless of the experiment, were used to conclude that they are genuine baryons and not merely the consequence of dynamical rescatterings. These baryons cannot be associated with classical q³ quark configurations. We associate them with two colored-quark cluster configurations.

PACS
14.20.Gk - Baryon resonances with S=0 .
12.40.Yx - Hadron mass models and calculations.
13.75.Cs - Nucleon-nucleon interactions (including antinucleons, deuterons, etc.).
14.20.Pt - Dibaryons.

© Società Italiana di Fisica, Springer-Verlag 2003