K̄ and nucleus system studied by 12C(K−, p) spectrum

We have measured an inclusive missing-mass spectrum of the 12 C(K−, p) reaction over wide energy region at the kaon incident momentum of 1.8 GeV/c at J-PARC K1.8 beam line. This measurement was carried out as a by-product of a pilot run of J-PARC E05 experiment, which searched for the Ξ-hypernuclei via 12C(K−, K+) reaction. We have compared the observed missing-mass spectrum with a DWIA calculation to study the K-nucleus interaction. In this comparison, we have changed the depth of both real and imaginary parts of the optical potential between the K and nucleus. It is found that the observed spectrum is best reproduced by the calculation of the potential depth of V0 ∼ −80 MeV (real part) and W0 ∼ −40 MeV (imaginary part). On the other hand, we have observed a definitive excess around the deeply bound region BK ≳ 100 MeV. The excess cannot be explained by the any optical potential and quasi-free background reaction. It is well fitted with a Breit-Wigner function with a binding energy of 90 MeV and a width of 100 MeV, which can be interpreted as a deeply bound Λ(1405) nucleus.We have measured an inclusive missing-mass spectrum of the 12 C(K−, p) reaction over wide energy region at the kaon incident momentum of 1.8 GeV/c at J-PARC K1.8 beam line. This measurement was carried out as a by-product of a pilot run of J-PARC E05 experiment, which searched for the Ξ-hypernuclei via 12C(K−, K+) reaction. We have compared the observed missing-mass spectrum with a DWIA calculation to study the K-nucleus interaction. In this comparison, we have changed the depth of both real and imaginary parts of the optical potential between the K and nucleus. It is found that the observed spectrum is best reproduced by the calculation of the potential depth of V0 ∼ −80 MeV (real part) and W0 ∼ −40 MeV (imaginary part). On the other hand, we have observed a definitive excess around the deeply bound region BK ≳ 100 MeV. The excess cannot be explained by the any optical potential and quasi-free background reaction. It is well fitted with a Breit-Wigner function with a binding energy of 90 MeV and a widt...