  We study the Cauchy problem for the Klein-Gordon-Zakharov system in 3D with
low regularity data. We lower down the regularity to the critical value with
respect to scaling up to the endpoint. The decisive bilinear estimates are
proved by means of methods developed by Bejenaru-Herr for the Zakharov system
and already applied by Kinoshita to the Klein-Gordon-Zakharov system in 2D.
