Results of the J-PARC E27 experiment

Ichikawa, Yudai   ; Imai, Kenichi

While the existence of kaonic nuclei has been intensively studied both theoretically and experimentally, there is no conclusive result establishing its existence.Here, we have searched for the , a bound state of a with two protons, in the reaction at 1.69 GeV/ at J-PARC K1.8 beam line with a missing-mass resolutionof 2.7 MeV/(FWHM). In this reaction, the is assumed to be produced as as a doorwaysuch as , .Since the sticking probability of the on proton would not be so large, coincidence of high-momentum ( 250 MeV/) proton(s) in large emission angles () was requested to enhance the signal-to-background ratio. We have obtained an inclusive spectrum in a wide missing-mass range from , to /, for the first time. A proton coincidence spectrum shows a large proton-emission probability at around 2.27 GeV/ as a broad bump. It might be attributed to the production. A study of decay branch suggests non-mesonic decays of and are dominant rather than mesonic decays.