1. Ecole Polytechnique, Palaiseau 2. Laboratoire de l'Accélérateur Linéaire, Orsay 3. CEN, Saclay 4. College de France, Paris 5. CERN, Geneva
Abstract:
From π- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c2. Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex1 is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.