HADES

The $ppK^-$, a well established state in theory, is a hot candidate for a new kind of hadronic matter. A type of matter where kaons are bound to nucleons. The HADES spectrometer at GSI provides ideal conditions to test the existence of this cluster of particles. HADES has recorded $p+p$ collisions at a beam energy of 3.5 GeV that we have analysed for events where a $p$, $K^+$ and $\Lambda$ were produced in the final state. I will discuss how these three particles are connected to the $ppK^-$ and how we tested the $p$, $K^+$, $\Lambda$ events for the fingerprints of a possible $ppK^-$ production. In this talk, I will present how a partial wave analysis lead to the establishment of an upper limit of the production cross section of this cluster. We cannot confirm the findings of the DISTO collaboration at a lower beam energy of 2.8 GeV.