DISTO and FOPI – the search for strange di-baryons K–pp
DISTO has investigated the formation of kaonic states in the 3-body final state pΛK+. A binary process pp→XK+ in which an exotic kaonic state is produced could in fact lead through this decay chain to the pΛK+ final state. DISTO has very large and pure statistics. The observation of an X resonance with a mass of 2265 MeV/c2, called X(2265) and the energy dependence study of its production have been performed using what-we-call the deviation method, that was very powerful, however, with a certain limitation. We are working for a reanalysis making use of a full acceptance matrix, which will allow to investigate further the nature of the X(2265) and to study the Σ decay channel as well.
FOPI as well has been investigating the kaonic states in the same reaction as DISTO, i.e. pp→pΛK+ but at the proton incident energy of 3.1 GeV. The FOPI data provides an independent check of the X(2265) found by DISTO, as well as an extended energy dependence study.