The Landau-Pomeranchuk effect and soft lepton-pair production in heavy ion collisions

The most general angular decay distribution of the hadronic system in the decay of a polarized into one pseudoscalar plus a vector is calculated. Emphasis is put on decays ine ⁺ e ^– experiments where the neutrino escapes detection and the restframe cannot be reconstructed. We propose a model for the decay intov involving both a vector- and a second class axial vector-current contribution. Then we present numerical results for this decay channel.