The Lambda(1405) state in a chiral unitary approach with off-shell corrections to dimensional regularized loop functions

The Bethe-Salpeter equation is solved in the framework of unitary coupled-channel approximation by using the pseudoscalar meson-baryon octet interaction. The loop function of the intermediate meson and baryon is deduced in a dimensional regularization scheme, where the relativistic kinetic effect and off-shell corrections are taken into account. According to the experimental data at the $K^- p$ threshold, the subtraction constants in the loop function are determined. The squared amplitude is suppressed strongly and only one $\Lambda(1405)$ state is generated dynamically in the strangeness $S=-1$ and isospin $I=0$ sector.