AN EFFECTIVE CHIRAL LAGRANGIAN APPROACH TO KAON-NUCLEAR INTERACTIONS

摘要

On-shell kaon-nucleon scattering, kaonic atom and kaon condensation are treated on the same footing by means of a chiral perturbation expansion to the next-to-next-to-leading order (''N(2)LO''). Constraining the low-energy constants in the chiral lagrangian by on-shell KN scattering lengths and kaonic atom data, the off-shell s-wave scattering amplitude up to one-loop order corresponding to N(2)LO and the critical density of kaon condensation up to in-medium two-loop order are computed. The effects on kaon-proton scattering of the quasi-bound Lambda(1405) and on kaonic atoms and kaon condensation of Lambda(1405)-proton-hole excitations through four-fermi interactions are studied to ah orders in density within the in-medium two-loop approximation. It is found that the four-fermi interaction terms in the chiral lagrangian play an essential role in providing attraction for kaonic atoms, thereby inducing condensation but the critical density is remarkably insensitive to the strength of the four-fermi interaction that figures in kaonic atoms. The prediction for the critical density is quite robust against changes of the parameters in the chiral lagrangian, and gives - for ''natural'' values of the four-fermi interactions - a rather low critical density, rho(c) less than or similar to 4 rho(0). When the BR scaling is suitably implemented, the condensation sets in at rho(c) similar or equal to 2 rho(0) with loop corrections and four-fermi interactions playing a minor role. [References: 59]