Darmstadt 2008 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 35: Elektromagnetische und Hadronische Sonden

HK 35.6: Talk

Thursday, March 13, 2008, 18:00–18:15, 1C

Investigations on the Λ(1405) with WASA-at-COSY — •Wojciech Weglorz for the WASA-at-COSY collaboration — Institut für Kernphysik, Forschungszentrum Jülich — Nuclear Physics Department, University of Silesia, Katowice

The nature of hyperon resonance Λ(1405) is yet not well known. It is, for example, considered to be of non-triplet quark structure or a bound KN state. Recent calculations predict the Λ(1405) to have a two-pole structure, which has direct influence on the coupling of its πΣ decay modes with the pure Λ(1405) decaying through π⁰Σ⁰. One major difficulty in the experimental determination of the spectral shape of the Λ(1405) (width = 50 MeV) originates in its overlap with the Σ(1385) resonance (width = 36 MeV) while having the same charged πΣ decay channels.

The WASA-at-COSY setup with a close to 4π geometrical acceptance for charged and neutral particles allows to detect all final state particles of the decay Λ(1405)→π⁰Σ⁰→ (γ γ)_π⁰ (p π⁻ γ)_Σ⁰. In combination with the high density hydrogen pellet target and the COSY proton beam this provides the opportiunity to cleanly identify the Λ(1405) in the reaction pp → pK⁺Λ(1405) and to shed some light on its nature.

In this presentation the status of the feasibility studies are discussed.

Supported by FZ Jülich and BMBF.