ИСТИНА

Two unexcited strings or branes interacting via dilaton, antisymmetric form and gravitational fields may generate radiation in the collision process similar to bremsstrahlung of point charges in electrodynamics. We calculate these effects classically within perturbation theory in terms of interactions which is expected to be valid if the scattering angle is small. The first order interaction terms induce deformations of the extended objects which under certain conditions may move with superluminal velocities. Cerenkov radiation then arises in the second order approximation. The effect is not small with respect to radiation from oscillating closed strings and branes in brane gases and cosmic strings cosmological scenarios.