  We have calculated the KK bar --> KK bar scattering amplitude to next to
leading order in Chiral Perturbation Theory. Then, making use of a
unitarization procedure with one or several coupled channels (\pi\pi, KK bar in
our case) we have calculated the \pi\pi --> \pi\pi, \pi\pi --> KK bar and KK
bar --> KK bar S and P waves in good agreement with the experiment up to
\sqrt{s}= 1.2 GeV. The \pi\pi scattering lengths with isospin and spin (I,J)
equal to (0,0), (1,1) and (2,0) are also calculated in agreement with
experiment and former Chiral Perturbation Theory calculations. Finally we have
employed these amplitudes, making use of an Omnes representation, to calculate
the scalar and the vector pion form factors, obtaining a good agreement with
the available experimental data.
