The self-energy of the K^- meson in nuclear matter is calculated in a
self-consistent microscopic approach, using a \bar{K}N interaction obtained
from the lowest-order meson-baryon chiral Lagrangian. The effective \bar{K}N
interaction in the medium is derived by solving the coupled-channel
Bethe-Salpeter equation including Pauli blocking on the nucleons, mean-field
binding potentials for the baryons and the self-energy of the \pi and \bar{K}
mesons. The incorporation of the self-consistent {\bar K} self-energy in the
description, in addition to the Pauli blocking effects, yields a weaker
attractive in-medium {\bar K}N interaction and a \Lambda(1405) which dissolves
faster with increasing matter density, as a result of the {\bar K} spectral
function being spread out over a wide range of energies. These effects are
further magnified when the intermediate pions are dressed.Comment: 23 pages, 7 figures, ReVTe
