Radiative back reaction on global strings

We consider radiative back reaction for global strings using the Kalb-Ramond formalism. In analogy with the point electron in classical electrodynamics we show how local radiative correc-tions to the equations of motion allow one to remove the divergence in the self-field and calculate a first-order approximation to the radiation back reaction force. The effects of this back reaction force are studied numerically by resubstituting the equations of motion to suppress exponentially growing solutions. By direct comparison with numerical field theory simulations and analytic radiation calculations we establish that the "local back reaction approximation" provides a satisfactory quantitative description of radiative damping for a wide variety of string configurations. Finally, we discuss the relevance of this work to the evolution of a network of global strings and their possible cosmological consequences. These methods can also be applied to describe the effects of gravitational radiation back reaction on local strings, electromagnetic radiation back reaction on superconducting strings, and other forms of string radiative back reaction.