He, J (reprint author), Chinese Acad Sci, Inst Modern Phys, Div Theoret Phys, Lanzhou 730000, Peoples R China.
The octet meson and baryon interaction with strangeness S = -1 is studied fully relativistically with chiral Lagrangian. In this paper, a Bethe-Salpeter equation (BSE) approach with spectator quasipotential approximation is applied to study the reactions K- p -> MB with MB = K(-)p, (K) over bar (0)n, pi(-)Sigma(+), pi(0)Sigma(0), pi(+)Sigma(-) and eta Lambda with all possible partial waves and theoretical results are comparable with experimental data. It is found that the Weinberg-Tomozawa potential derived from the lowest order chiral Lagrangian only provides the contributions from partial waves with spin-parities JP = 1/2(+) and 1/2(-). Two-pole structure of the Lambda(1405) is confirmed with poles at 1383 + 99i and 1423 + 14i MeV. The lower and higher poles originate from Sigma pi interaction as a resonance and (K) over barN interaction as a bound state, respectively.