Evidence for an Excited Hyperon State in pp{yields}pK{sup +}Y{sup 0}*
- Andrzej Soltan Institute for Nuclear Studies, 05400 Swierk (Poland)
- High Energy Physics Department, Petersburg Nuclear Physics Institute, 188350 Gatchina (Russian Federation)
- Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany)
- Institut fuer Kernphysik, Universitaet zu Koeln, 550937 Cologne (Germany)
- University College London, London WC1E 6BT (United Kingdom)
Indications for the production of a neutral excited hyperon in the reaction pp{yields}pK{sup +}Y{sup 0}* are observed in an experiment performed with the ANKE spectrometer at COSY-Juelich at p{sub beam}=3.65 GeV/c. Two final states were investigated simultaneously, viz. Y{sup 0}*{yields}{pi}{sup +}X{sup -} and {pi}{sup -}X{sup +}, and consistent results were obtained in spite of the quite different experimental conditions. The parameters of the hyperon state are M(Y{sup 0}*)=(1480{+-}15) MeV/c{sup 2} and {gamma}(Y{sup 0}*)=(60{+-}15) MeV/c{sup 2}. The production cross section for Y{sup 0}* decaying through these channels is of the order of few hundred nanobarns. Since the isospin of the Y{sup 0}* has not been determined here, it could either be an observation of the {sigma}(1480), a one-star resonance of the Particle Data Group tables, or, alternatively, a {lambda} hyperon. Relativistic quark models for the baryon spectrum do not predict any excited hyperon in this mass range and so the Y{sup 0}* may be of exotic nature.
- OSTI ID:
- 20775001
- Journal Information:
- Physical Review Letters, Vol. 96, Issue 1; Other Information: DOI: 10.1103/PhysRevLett.96.012002; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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