Gießen 2007 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 50: Elektromagnetische und Hadronische Sonden
HK 50.7: Vortrag
Donnerstag, 15. März 2007, 18:30–18:45, A
Hyperon production in hadronic collisions at ANKE-COSY — •izabella zychor for the ANKE collaboration — Institute for Nuclear Studies, Swierk
Hyperons are produced at COSY in pp collisions. The maximal beam
momentum of 3.65 GeV/c allows to measure hyperons Y with masses
<1540 MeV/c2 in reactions induced by protons. It is essential
that the ANKE spectrometer permits the simultaneous observation of
different decay modes: Y → π0 Σ0, π∓Σ±, π0 Λ, K− p.
Indications for a neutral excited hyperon resonance Y0*(1480)
have been found in the reaction pp → pK+ Y0*
→ pK+π±X∓. Its parameters are M(Y0*) =
(1480± 15) MeV/c2 and Γ(Y0*) = (60±
15) MeV/c2 though, since it is neutral, it can be either a
Λ or Σ hyperon. On the basis of existing data we
cannot decide whether it is a three–quark baryon or an exotic state.
The Λ(1405) is a particularly interesting baryonic state
because its structure is not yet understood and it is difficult to
obtain in quark models. Recent theoretical investigations based on
chiral dynamics predict two poles for the Λ(1405). The
missing and invariant mass techniques are used to identify the
Λ(1405) resonance decaying via Σ0π0.
An overview about new results from recent hyperon experiments
performed at ANKE/COSY will be presented.
Supported by FZJ, BMBF, DFG