On a $Z^{\prime}$ signature at next high energy electron-positron   colliders
  The associated production of a $Z^{\prime}$ and a final hard photon in high energy electron-positron colliders is studied. It is shown that the hard photon spectrum contains useful information on the $Z^{\prime}$ properties. This remark suggests that, if a new neutral gauge boson exists for $M_{Z^{\prime}} < \sqrt{s}$, it will not be necessary to make a new energy run at the $Z^{\prime}$ mass in order to get most of its properties. 
F. M. L Almeida Jr, Y. A. Coutinho, J. A. Martins Sim\~oes, A. J.   Ramalho, S. Wulck, M. A. B. do Vale