Landau's hydrodynamic model of particle production and electron-positron annihilation into hadrons

The hydrodynamic model of Landau is formulated in very general terms and applied to the determination of average energy of secondaries, and single-particle inclusive distributions of secondaries. Attention is focused on the relationship between various dynamical assumptions and the equation of state assumed for the fluid motion. In the regimes of scaling and approximate scaling, we solve analytically the hydrodynamic motion of the fluid for both pp→π+X and e⁺+e^-→π+X. For the annihilation process we solve the hydrodynamic equations numerically and discuss the validity of the scaling approximations. Explicit comparison is made between two dynamical models, the ultrarelativistic model (ideal-gas model) and the hadronic spectrum model.