Hard spectra and QCD matter: experimental review
  The most significant experimental results on hadron spectra at large transverse momentum available at the time of Quark Matter 2004 conference are reviewed. Emphasis is put on those measurements that provide insights on the properties of the QCD media, ``Quark Gluon Plasma'' and ``Color Glass Condensate'', expected to be present in nucleus-nucleus collisions at collider energies. 
David d'Enterria