Result of 12C(K-, p) analysis of the J-PARC E05 pilot run

We have measured an inclusive missing-mass spectrum without any trigger biases of the 12C(K-, p) reaction at the kaon incident momentum of 1.8 GeV/c. This data was taken as a by-product of the J-PARC E05 pilot run, which aim to search for the Xi-hypernuclei. We have obtained the spectrum in high statistics and high energy resolution of 4.2 MeV (sigma) in a wide energy region of BK = -700 to 300 MeV. The spectrum was compared with a DWIA calculation based on the Morimatsu-Yazaki Green's function method, in which the complex Kbar-nucleus potential U = V + iW is an input parameter. The spectrum in the quasi-free Kbar-n scattering region and Kbar bound region were fitted with these calculations. The observed spectrum around the quasi-elastic and shallow binding energy region is well reproduced by the calculation of the potential depth of V ~ -80 MeV and W ~ -40 MeV. Here, we have observed the definitive excess in large binding energy region BK > 100 MeV. Namely, we can not find a potential parameter set which reproduces this excess. We may need to consider energy-dependent potentials including multi-nucleon absorption processes. A possible interpretation of this excess is the existence of the bound state between Lambda(1405) and 10Be system.