Partial wave analysis of the reaction p(3.5 GeV) + p -> pK(+) Lambda to search for the "ppK(-)" bound state
Employing the Bonn-Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction p(3.5 GeV) + p -> pK(+) Lambda. This reaction might contain information about the kaonic cluster "ppK(-)" (with quantum numbers J(P)=0(-) and total isospin I=1/2) via its decay into p Lambda. Due to interference effects in our coherent description of the data, a hypothetical (K) over bar NN(or, specifically "ppK-") cluster signal need not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectrum like p Lambda. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a (K) over bar NN cluster. At a confidence level of CLs=95% such a cluster cannot-contribute more than 2-12% to the total cross section with a pK(+) Lambda final state, which translates into a production cross-section between 0.7 mu b and 4.2 mu b, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.