Prompt production of light-flavour mesons

The conditions under which the higher twist mechanism may contribute to produce mesons at large pT in hadronic interactions are carefully examined. A part from applicability conditions of perturbative QCD, it is proved that one only has to require the prompt meson to be of large rapidity in the center of mass system of the incoming partons. A method which allows to deal simultaneously with S- and P-wave mesons is explained. The main consequence of this analysis allows to conclude that the shapes of the higher twist contributions are well predicted, while their absolute size may be subject to questions. Experimental channels which chould give support to the higher twist mechanism are reviewed. Finally an unambiguous signature of the glueball nature of 2++ mesons is given. (orig.)