Radiative Decays of Low-Lying Excited-State Hyperons
- Rice Univ., Houston, TX (United States)
The quark wave-functions of the lower-lying excited-state hyperons Lambda(1405), Sigma(1385), and Lambda(1520) are not well understood. For example, the Lambda(1405) may not be a regular three-quark state but a $$\bar{K}$$N molecule. Several competing models have been proposed, but none have been convincingly eliminated. Measuring radiative decays provides a means of discriminating between the models. The radiative branching of ratios are predicted to be small (~1%), but the radiative widths vary by factors of 2-10 from model to model. The existing experimental data is sparse and inconsistent; moreover, the radiative decay of the Sigma(1385) has never been observed before (except for one event). These lower-lying excited state hypersons were produced in a tagged photon-beam experiment in the CLAS detector at TJNAF in the reaction gamma p → K+ Y* for photon energies from threshold to 2.4 GeV. The radiative branching ration for the Sigma0(1385) relative to the Sigma0(1385) → Lambda pi0 channel was measured to be 0.021 ± 0.008$$+0.004\atop{-0.007}$$, corresponding to a partial width of 640 ± 270$$+130\atop{-220}$$ keV.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 824879
- Report Number(s):
- JLAB-PHY-00-67; DOE/ER/40150-2737; TRN: US0402190
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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