The γn→K+K-n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54±0.01 GeV/c2 with a width smaller than 25 MeV/c2 and a Gaussian significance of 4.6σ. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uudds̄) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.
Physical Review Letters
- Pub Date:
- July 2003
- Baryon production;
- Meson production;
- High Energy Physics - Experiment
- 12 pages, 3 encapsulated postscript figures