München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 36: Theorie
HK 36.2: Gruppenbericht
Mittwoch, 22. März 2006, 17:00–17:30, B
Coupled-channel study of crypto-exotic baryons with charm — •Julian Hofmann and M.F.M. Lutz — GSI, Planck Str. 1, 64291 Darmstadt
Identifying a zero-range exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, a rich spectrum of molecules is formed. We argue that chiral symmetry and large-Nc considerations determine that part of the interaction which generates the spectrum. An anti-triplet of bound states with negative charm is predicted. We suggest the existence of strongly bound crypto-exotic baryons, which contain a charm-anti-charm pair. A narrow nucleon resonance is found at mass 3.52 GeV. It is a coupled-channel bound state of the (ηc N), (D Σc) system. This resonance is part of an octet. Furthermore a singlet hyperon states at mass 3.23 GeV is observed as a consequence of coupled-channel interactions of the (Ds Λc), (D Ξc) states. Most striking is the small width of about 1 MeV. The octet states may be significantly broader due to a strong coupling to channels containing an η′. The two so far observed s-wave baryons with charm one are recovered. We argue that the Λc(2880) is not a s-wave state. In addition to those states we predict the existence of about ten narrow s-wave baryon states with masses below 3 GeV.