Document Type

Article

Article Version

Publisher's PDF

Publication Date

1-1-2004

Abstract

The reaction γp→π+K−K+n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3–5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555±10  MeV/c2 was observed in the nK+ invariant mass spectrum. The peak’s width is consistent with the CLAS resolution (FWHM=26  MeV/c2), and its statistical significance is (7.8±1.0)σ. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Θ+ baryon. In addition, the pK+ invariant mass distribution was analyzed in the reaction γp→K−K+p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Comments

Copyright American Physical Society Publisher final version available at http://prl.aps.org/pdf/PRL/v92/i3/e032001 and http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.92.049902

Publication Title

Physical Review Letters

Published Citation

V. Kubarovsky et al. [CLAS Collaboration], "Observation of an exotic baryon with S = +1 in photoproduction from the proton", Phys. Rev. Lett. 92, 032001 (2004) [Erratum- ibid. 92, 049902 (2004)] DOI: 10.1103/PhysRevLett.92.032001

DOI

10.1103/PhysRevLett.92.032001

Peer Reviewed

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