Radiative Decays of Low-Lying Excited-State Hyperons

Thesis/Dissertation · Mon May 01 04:00:00 EDT 2000

DOI:https://doi.org/10.2172/824879· OSTI ID:824879

Taylor, Simon ^[1]

---

1. 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 Energy Research (ER)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 824879
• Report Number(s): JLAB-PHY--00-67; DOE/ER/40150--2737
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
EXCITED STATES
HYPERONS
PHOTONS
QUARKS
RADIATIVE DECAY
WAVE FUNCTIONS