A search for deeply bound kaonic nuclear states
  We have measured proton and neutron energy spectra by stopping negative kaons on liquid helium4. Two distinct peak structures were found on both spectra, which were assigned to the formation of new kinds of strange stribaryons. In this paper, we summarize both results. 
T. Suzuki, H. Bhang, G. Franklin, K. Gomikawa, R.S. Hayano, T.   Hayashi, K. Ishikawa, S. Ishimoto, K. Itahashi, M. Iwasaki,...