1212.4951 (Takayasu Sekihara et al.)

Mesonic and non-mesonic branching ratios of K^- absorption in the
nuclear medium    [PDF]

Takayasu Sekihara, Junko Yamagata-Sekihara, Daisuke Jido, Yoshiko Kanada-En'yo

The branching ratios of K^- absorption at rest in nuclear matter are evaluated from the K^- self-energy by using the chiral unitary approach for the s-wave \bar{K} N amplitude. We find that both the mesonic and non-mesonic absorption potentials are dominated by the \Lambda(1405) contributions. We also observe that the mesonic absorption ratio [\pi ^{-} \Sigma ^{+}] / [\pi ^{+} \Sigma ^{-}] increases as a function of nuclear density due to the interference between \Lambda(1405) and the I=1 non-resonant background, which is consistent with experimental results. The ratio [\pi ^{-} \Sigma ^{+}] / [\pi ^{+} \Sigma ^{-}] becomes unity at relatively lower density, which means that the peak position of the \Lambda(1405) spectrum in K^{-}p \to (\pi \Sigma)^{0} should be at an energy close to the \bar{K} N threshold rather than at 1405 MeV. The non-mesonic absorption ratios [\Lambda p]/ [\Sigma ^{0} p] and [\Lambda n]/ [\Sigma ^{0} n] are about unity while [\Sigma ^{+}n]/[\Sigma ^{0}p] and [\Sigma ^{-}p]/[\Sigma ^{0}n] are about two due to the \Lambda(1405) dominance in absorption. The fraction of the non-mesonic absorption is evaluated to be about 30 % at the saturation density.

View original: http://arxiv.org/abs/1212.4951