Low-Energy Antikaon Interaction with Nuclei: The AMADEUS Challenge

Abstract

The low-energy strong interaction of antikaons (K − ) with nuclei has many facets and represents a lively and challenging research field. It is interconnected to the peculiar role of strangeness, since the strange quark is rather light, but still much heavier than the up and down quarks. Thus, when strangeness is involved one has to deal with spontaneous and explicit chiral symmetry breaking in QCD. It is well known that the antikaon interaction with nucleons is attractive, but how strong ? Is the interaction strong enough to bind nucleons to form kaonic nuclei and, if so, what are the properties (binding energy, decay width)? There are controversial indications for such bound states and new results are expected to come soon. The existence of antikaon mediated bound states might have important consequences since it would open the possibility for the formation of cold baryonic matter of high density which might have a severe impact in astrophysics for the understanding of the composition of compact (neutron) stars. New experimental opportunities could be provided by the AMADEUS experiment at the DAΦNE electron-positron collider at LNF-INFN (Frascati, Italy). Pre-AMADEUS studies on the antikaon interaction with nuclei are carried out by analysis of data collected by KLOE in till 2005 and in special data runs using a carbon target insert. Studies for the dedicated AMADEUS detector setup taking advantage of the low-energy antikaons from Φ-meson decay delivered by DAΦNE are in progress. Some results obtained so far and the perspectives of the AMADEUS experiment are presented and discussed.

Testing chiral unitary models for the $Λ(1405)$ in $K^{+}πΣ$ photoproduction

“…Completely new experimental data on the isoscalar π 0 Σ 0 photoproduction should also be reported soon by the GlueX collaboration [44]. Other efforts aim at determining the isovector part of the KN interaction via precise measurements of the kaonic hydrogen and kaonic deuterium characteristics [45][46][47] or by studying the related K 0 L p → K + Ξ 0 reaction [48]. Finally, exciting new prospects in exploring strangeness in the hadron spectrum may open with the PANDA experiment [49,50].…”