Spectral characteristics of scalar higher-dimensional bremsstrahlung

We consider scalar higher-dimensional bremsstrahlung to explore the possibility of classical probes of extra dimensions, since higher-dimensional Minkowski space-time is a flat limit of cosmological backgrounds. The applicability of this results to models of ADD type has been proven by Galtsov, Kofinas, Spirin, and Tomaras in a number of papers. We develop classical perturbation theory which describes interaction between point particles moving on the observable 3-dimensional space, that simulates a 3-brane, and mediated by scalar fields. Applying this to the scattering problem, we find that the scattering angle is finite and contrary to the corresponding quantum result. Then we calculate scalar bremsstrahlung from ultrarelativistic particles colliding in D-dimensional Minkowski space and show that the radiation loss increases as a power of the Lorentz factor γ of the collision, increasing with D.